Rego Forumen or Rego Computorem perhaps?
It's still a fun topic to discuss, though. And in many ways quite a lot more interesting now that all 12 houses have had far more detail fleshed out over the intervening decade.
So in the interests of the original discussion:
Current saga:
1 Verditius, 2 Tytalus, 1 Ex Misc., 1 Tremere
Previous saga:
Every house except Merinita, with a considerable number of double-ups and the occasional triple.
Current Saga
- Guernicus - Gentle Gifted Intellego specialist
- Bonisagus - Lab specialist (10 years past gauntlet and only just now got an art past 7)
- Bjornaer - MuHe specialist
- Mercere - Shapeshifting master, hatched nine children so far (seven of them Gifted)
- Verditius - Rego specialist, left to be a faerie queen
- Flambeau - PeVi specialist, Merinita in all but name, player kicked out of game
My current Saga has 2 verditi, a bonisagus, a merinita, a flambeau, a redcap of mercere, and a tremere rebel as player characters, and a second flambeau, three bonisagi (one of whom is a rat, another of whom is a ghost), a gernicus quaisitor, a second tremere and an ex misc as NPCs in the same covenant.
Looking at the overall numbers of the thread thus far. The clear winner is House Ex Miscellanea, with House Bjornaer & House Merinita a close second & third respectively. It drops appreciably to Bonisagus, Flambeau, & Tytalus (in that order). Tremere, Criamon, and Verditus trail slightly behind and are essentially tied amongst each other. Mercere is notably lower than the rest. Guernicus is by far the least popular House of the list.
In my Saga we have:
1 Flambeau
1 Verditius
1 Merinitas
2 Ex Misc (one of which is a Holy Magus)
And no Diedne either! What's with that?
I don't encourage players to take instant death Virtues. The covenant has four Flambeau magi and a Tremere present.
First they'd have to detect he is a Diedne. Not trivial, since no one has seen a Diedne in over 200 years. No one knows what non-standard magics they really had.
And second... 
Last game: 1 Bonisagus, 1 Jerbiton, 1 Flambeau, 1 Tytalus.
Game before: 2 Bjornear, 2 Bonisagus, 1 Jerbiton, 1 Quaesitor.
2 Tremere (One with Hermetic Prestige, working as an honorary Quaesitor. The other, to his shame, is a leper)
1 Verditius (with the blood of a Zmaj)
1 Ex Miscellanea (Lineage of Pralix, studying Storm wizards)
1 Jerbiton (Rego Craftsman, diplomat between Theban and Transylvanian tribunals)
Current Saga 1:
Now: 5 Merinitae, 1 Verditius.
Earlier: 4 Merinitae, 2 Mercere.
... the merinita-density comes from the Covenant concept.
Current Saga 2:
1 of each of: Boisagus (Trianoma), Ex Miscellanea, Flambeau, Tremere, Verditius.
Earlier sagas: I think I've seen multiples of every house except Criamon - in this edition.
Earlier editions have tended to have plenty of Criamons.
Current saga 1: Tytalus
Current Saga 2: Mercere
Current saga 3 (pbp): Verditius, in the Pathfinder setting.
Previous sagas have been Bonisagus (twice), Tytalus and Flambeau. One aborted saga I tried a Merinita, I almost don't count it.
Current Saga, Provence-Tribunal:
Jerbiton (good old Pontifex)
Bonisagus (researches weapons against the Infernal, christian touch)
Flambeau (boom!)
Ex Miscellanea (kind of witch from romania)
Tytalus (dark Titanoi)
Criamon (on the path of walking backwards)
Current Saga Rhine-Tribunal:
Tremere (ambitious)
Bjornaer (nightingale)
Guernicus (first the covenant, then the house, at last the order)
Jerbiton (with extraordinary faerie-roots)
Note, in my post above that's what I've played or currently playing. In all of the past sagas and all of the current sagas I have seen every House in play.
My favourirte character I ever played in ArM5 was a oread (moutain nymph)-blooded Bonisagius who had mercurian magic. She was a specialist in Magic Theory and Vim, and most of her spells had a slight faerie touch when it came to the names or intent). It was very fun to play a Bonisagius, though a genious reseacher, but who spent at least 1 season per year to be better with painting and/or dancing.
I wish I had time and opportunity to play them all! Honestly, I'd love the chance to play in a few sagas and have a Flambeau here, and a Criamon there, and then a Bjornaer to follow.
I've played... Tytalus, Bonisagus, Ex Miscellanea, and Verditius. Mainly. But I've spent so much time as storyguide that I kind of get to scratch each different itch afforded by each House.
They've all got a ton of fun to offer.
Campaign in Which I play
Three Bonisagi (Two Bonisagi, one Trianoma)
One Ex Misc
One Flambeau
One Merinita
One Criamon
One Gifted Mercere (Me)
Campaign for which I am SG
One Tremere
One Bjorner
One Verditius
One Criamon
One Bonisagus.
Never seen a PC guernicus.
We play in the Rhine Tribunal and our Covenant consists of:
1 Bonisagus
1 Ex Miscellanea
1 Flambeau
1 Guernicus
One in a club with a Bjornaer, a Flambeau Ramius, a Guernicus, a Tytalus, a Bonisagus (in Iberia)
One on line with two Flambeau (Ebroin/Animal and the other the penetration school described in Hibernia), an ex-misceleana Pharmacoepian and Folk Witch, a Merinita folk mysteries, a Tytalus Bonisagus (his Tytalus master was merched) ans a Verditius (the only one not being hibernian).