Back when this board started there was a thread on what everyone's favorite house was. In fact it was thread #3
https://forum.atlas-games.com/t/favorite-houses/91/1
Now we've seen the other two house books, let's see how opinions have changed.
What's your favorite house? Why?
Well, I'll chime in. There are two answers:
As written, I would say Ex Misc. Mostly because of the flexibility of what an Ex Misc magus is and the bredth of concepts discussed. The diversity of the House is very interesting to me.
Conceptually, I waffle between Tytalus and Flambeau. They seem to be more of the "Go! Do!" types, generally. All magi are scholars of a sort, of course, but these seem to be about excellence in practice.
Just my two cents.
-K!
I know they get a lot of flak as the mangled poster-boys of White-wolfdom, but I find the current incarnation of Tremere as the First Hermetic Legion pretty well done. I think they're probably least "true lineage"-y of the True Lineages, and their organization and culture provide for a lot of story hooks for interesting magi. They probably tie with Tytalus and Flambeau for "Easiest Choice as an Antagonist" but Tremere have a great deal of potential very complex inter-magi relations. (Not that other magi can't or don't, but Tremere have it built in with their internal house politics and external positions on other houses that the other houses are hard pressed to match, in my opinion.)
-Ben.
I would say Tytalus and Tremere for the background stuff, and Bjornaer for the most positive change from the previous edition. I really liked the addition of Inner Mysteries for the Mystery Cults in 5th edition. 
Eirik
At first I was struck wit immense inspiration no matter what House I read about. Very good background and inter-House descriptions.
I haven't played that many different Houses during my Ars years. My early favorite was Criamon. I tried out a little Tremere, but that didn't catch on. I had such great succes with a 4th ed Flambeau, that she'll be re-created to fit into a new 5th ed campaign.
Bjornaer really interests me, more now than ever. Flambeau went from violent types to Champions, and perhaps interested me the most.
Jerbiton: makes freer character concepts possible.
Ex Misc: very much virtues and have no limits by house.
I would like Tremeres without their focus.
Sure, Jerbiton has also been much better described than just "interested in worldly, mundane arts and academics". Jerbiton has never been a house I yearned for, but it's a much more likely choise to me now.
I find the Bonisagus chapter quite good, Original Research is much clearer and with working results along the way, rather than just a looooong series of lab seasons, which might og might not yield anything. The new way, you're at least left with a bunch of warped spells or other lab projects. And finally some more about the Trianoma faction.
Mercere have also been expanded a great deal, with more options than just 'postman' for the Redcaps
The Merinita section has been much improved with regards to Faerie magic and -mysteries, I think it's more compatible with Hermetic than in the system in 4th ed in WGRE. The Nature path was also sorely missed by me in the previous edition.
I think the Criamon have become much stranger and obscurely philosophical, in a fascinating way, and much better described. I don't know if I'll jump the Criamon train again, not without much reading and re-reading.
Tremere rock my world. I always tend to lean towards characters that "build" in most RPG's, whether its evil empries (tm), armies, secret societies or fortresses and Tremere appeal to my organisational feelings. I like the idea of a rigidly organised group that builds for all eventualities.
Other than that, Criamon are interestingly obscure, Tytalus are supremely fun to play (so many fingers in so many pies). I'm even getting into flambeau in the brave champion type mold.
The only house that really doesn't do anything for me is Jerbiton. Never have done.
Tytalus: Inspirational characters:)
Tytalus, Tremere, and Bjornaer, in that order.
Tytalus because they did come off as both inspirational and intriguing (no pun intended), and because their presentation came off as far more coherent than many in the HoH series, from a fiddly bits AND a philosophical perspective. I could easily imagine playing a character from this House, and felt really grounded in the "what to do" realm. Finally, I laughed in several places while reading the chapter. The part about the division between Buliste and Harpax and how much the House enjoys it knocked me over.
Tremere because it's an awesome retcon from the old Vampire house stuff introduced by White Wolf. Someone said it's like the Tremere are now the Marine Corps, which is a decent shorthand way of describing their current militaristic incarnation. They're now noble and tragic and yet still the authoritarian element in a mostly democratic institution. There's nice tension there. The game I'm running is set in the Transylvanian Tribunal, so this chapter gave me a metric ton of material to work with.
Bjornaer because it's much easier to see what this House is about now, plus the variety of Heartbeast Mysteries give characters some cool stuff to shoot for beyond Art and Spell accumulation. I've always felt Bjornaer had a fuzzy agenda. The tension with House Merinita and the Huntress of the Wood also made for interesting story hooks. In our current game, my wife is playing a Bjornaer, and this chapter is giving her a lot to work with.
Edited to add my reasons why.
Very surprised by the tremere. I didn't like them before, but I love their new incarnation as the order's army. As birbin said, too bad they can't have a focus other than certamen 
Ex Miscellanea was good before, but now it rocks. It really feels diverse, even moreso now that the traditionnal stereotype of the "hedge wizards house" has been swept away. I really liked the pralixian lineage, too.
Flambeau were just big bullies to me before. Their new role as knights, adventurers and still bullies is great, and gave me the desire to play one.
I also loved the nature mysteries, I wanted some from a long time. The verditius ones, too, even if I dislike hubris.
All in all, pretty good job on all the houses, it's both impressive and attractive, and I can't think of a single house I wouldn't like to play.
I like all nearly all the new Houses. Never got to play one for more than a few sessions, though. It's hard to choose one.
My favorite house probably remains Criamon. I like their newfound wacko theories, I think they provide a nice focus and areas of interest. I like playing fairly orthodox new Criamon, except perhaps for the pacifistic part and that I find it hard to limit my spellcasting.
I also like to play the "pagan revivalist", which fits well with True Merinitia or Huntress in the Woods Bjornaer; I don't really like either House Merinitia or House Bjornaer as a whole, though. I just don't like the faeries, so no Merinitia. And while Bjornaer is far better than it was, I still find it kinda confused and aimless - animal ancestors?! With some tweaks, seeing Bjornaer as a mystery cult of "shapeshifters" that sees their true nature as beings of magic rather than mere humans, I could play a Bjornaer happily - but this is a far distance from the House as written. House Ex Misc also serves well for a rivavalist, and I appreciate the new extensive rules, but otherwise I don't find the House changed much.
I'd also like to play a Jerbiton serving as a knight of Nicea (the Code be damned), trying to restore it to its rightful place and put history back on track. I liked the new focus on the City and Eastern culture. But this is a very specific role fit for a very specific campaign, and I can't seem to pull off politics very well.
These are probably my favorites. I also liked how Tremere was depicated but find them a little hard to run (no focus or vote, lots of house-specific politics...), and how Tytalus was explained (really adds depth to their roleplaying). I mostly like the other Houses better than the old ones, but they're just not my favorites.
I didn't like the new Verditius' hubris (I see it as highly limiting their character), or that mundane vandettas matter in their history. It is probably my least favorite house as written, because of this, even though it has some great bits. I also don't like Bjornaer's ancestor-worship, or its myriad subdivisions, making it my second last choice as written - again, despite excellent ideas on the House, its history, the mysteries, and so on.
I'd have to say, given the new write-ups, that Bjornaer is at the top of my list, followed either by Flambeau (which still amazes me -- a one-trick-pony house done given such depth!) or Merinita (the "I can make a House all on my own!" approach). And Bonisagus still works well for me -- the House of specialists and researchers.
House Bonisagus has always been my favourite - the concept of the archetypal magical researcher leaves a lot of scope for variation between individual magi and the inherent idealism of the House appeals to me somewhat (although I have quite a bit of fun in my sagas with Bonisagi who are anything but idealistic). HoH:TL hasn't altered my perceptions very much, and there's nothing in the Bonisagus chapter that I take exception to.
I also like the fact that a lot of the inherent malevolence of House Tremere in previous editions has been taken out. Tremere himself may have been a power-mad headcase, but the TL chapter fits in much better with the basics provided in ArM5, p.12: "a sensible and stable house, providing strength and courage when needed and refraining from action when peace better serves the Order." And thank goodness the vampires are gone.
One thing that I'm not so sure about with House Ex Miscellenea is the Lineage of Pralix - I personally figured that as Pralix was Tytalus' apprentice she and her descendants would have picked up something of the same affinity for necromancy and spirit magic. The Comprehend Magic ability is very nice but I think that in my saga it'll end up as the speciality of another Ex Miscellenea tradition.
Oh yes!!! This was really a burden
But even this was well done, with the passage on dhampir, so those SG who like it may still have it.
One thing that struck me in all the books was the increased passion in the histories. Tytalus, for instance, despite the Nietzchean philosophy and challenges, had at least one, possibly two (if you count Pralix) great loves in his life. Tremere, on the other hand, seems to have departed with even a goodly portion of his House hating him. Bonisagus also comes off as a real human being, as do Mercere and Criamon. I found the interlocking stories of the Founders one of the most fascinating elements of the books. Looking back at my 3d edition HoH and remembering the 2d edition one, I'm impressed in how deeply the narrative has matured.
The only house I'm not as grabbed by is Verditius, though the author did a good job. I think the inherent problem is that the House as a whole is just so inward-focused and specialized toward the off-stage laboratory stuff, it's hard to make them dramatically interesting. Virtually all of the new Mysteries are for off-stage use, better suited for a Saga with a fast-paced timeline.
Verditius is my favourite and personally, I quite like hubris.. I don't find it restricting at all, given the fact you can flavour it in different ways to suit your magus.
And while it's true a fair amount of a verditius' power comes from spending seasons doing stuff.. that's true of quite a lot of things in ars anyway.. how long do you think it takes bonisagi to do stuff?.. research takes decades. My verditius was one of the more active magi of our campaign, and pretty characterful.
Despite the fact he many times longed to just be left alone and get work done, in the end, he always ended up going along with whatever wacky scheme happened to be going on at the moment, just because deep down, he felt he was the only truly competent magus in the covenant, and if he didn't go along, the others would mess everything up ^^
His hubris and personality flaw were proud.
I'm rambling again anyway.. but in short, just because a lot of their skills are handy in season length times, doesn't make a mage any less of a fun character to play.. plus, make a good item, and it's so much better than some other mage who spent the time just making a new spell ^^
I've been astonished by the new depth of houses Flambeau and Tytalus; quite neutral about Merinita and Ex Misc (nothing very new) and hated Criamon; the rest is just plain excellent.
Houses Verditius and Mercere have always been my favourites, I'd add in Flambeau now, and drop Criamon.
Criamon went from my absolute least favorite house to one of my most favorite. Criamon was the house that improved the most for me with its fifth edition write up.
Tytalus dropped in my esteem as the philosophy of the house emphasized self improvement less and tyranny more.
Flambeau climbed mightily in my esteem as it went from what I considered a fairly shallow house (though not as shallow as I found the old Criamon to be) emphasizing a deep respect for destroying things to the house that has the most medieval outlook and the house that might fit the best in many of the Ars saga I've seen played.
I'm personally OK with the hubris aspect of the new Verditious but if I had been playing a Verditious or had Verditious house politics playing a part in my game I'm certain that it would have disturbed me greatly. However coming into the house without a lot of verditious in my setting I found the new verditious a solid improvement over what we had before. (I think that the mystery of verditious elder runes is too powerful and the mystery of automata is too weak, but that's mechanics not the house itself)
Choosing a favorite house is now a much harder decision than it was two years ago. If forced to choose I'd probably say Bonisagus although Tremere, which was my favorite house back in the days of second edition before there was a vampire game or vampire plot, would be a strong contender as would houses Flambeau and Criamon
I think I'd drop the hubris.