Half the time my current characters familiar cant be bothered to come along because of the hassle. It would much rather hang out in a comfy heated lab with good food than it would like to be "in the field".
It usually requires a good reason beyond just "I would like to have the use of your powers".
Yes. I've come around on Mighty familiars.
Intelligence? Sure. Give me more!
But their powers are not that useful, unless non-hermetic or of a high enough level that you can't do it on your own.
I admit, I am working under the implication that an animal without a Might score will be forced to have cunning, and if something happens to give that animal an intelligene score, it will become a Magical animal.
I don't think that's the case under RAW, but even so. Why would I want a familiar with a high Might score? Unless I'm a combat magus of some sort?
Admittedly, I tend to play lab rats, but most of my familiars have had Might scores in the 5-10 range. I don't think my current familiar even has a score at all (she does have Int +1 though).
We've had those too. Mind you, one of my characters was kinda in the opposite situation:
Another member of the Troupe thought my character was too lazy and inactive (probably true), so gave him an active, "alpha-personality" familiar, who then pushed my poor character around a bit.
You would want that because the creature that you fall for has a high might score.
I think it is important that we remember not to make the choice of familiar into too much of an actual choice on the part of the magus and/or player. The game explicitly compares the familiar bond to a marriage. Humans dont generally only marry for gain, they do so because of circumstances beyond their control. Maybe your timid lab-rat of a magus ends up finding a perfect match soul-mate that is a high-might non-bookish powerhouse of a combat creature.
On the same note, my own characters familiar is not actually averse to going on adventures as a principle. It just tends to prefer different kinds of adventures. I play a lab-rat magus who generally goes on adventures to either deal with problems that threaten my characters ability to shut herself inside her lab all day. My characters familiar is an insufferable romantic who mostly wants to go on adventures that have knights in shining armor defeating dragons in them, or better yet adventures that see star-struck lovers getting married and/or eloping together. This results in a negotiation, a la "I will go on an adventure with you if you go on one with me".
I bring this up because I think it is an important dimension of the magus-familiar relationship that is often overlooked, in this thread too: That the relationship is precisely that: a relationship. A familiar should be more than just a boost to some stats. If a familiar is reduced to being a series of bonuses to various stats, lab total, combat ability, useful powers to cast on ones behalf, etc. It gives a skewed picture of what makes a good familiar. IMO a more powerful/intelligent familiar is much more likely to also be more demanding, which acts as an important balancing factor to having a powerful familiar.
My group has two options for a familiar. A player can design their own one, using the Grog power level. Or they can have another player design (and play) one, using the Companion power level. We all went with the second option.
Funny thing is, having a more powerful familiar isn't the primary reason. Having someone else design and play the familiar greatly increases the role playing options available. It results in familiars who are a more rounded character rather than a cardboard cutout of stat/lab boost.
From the experience I have gained, I firmly believe that having another player create and run a familiar is a good thing.
It's not just about combat stats. It's about having respect and interest in the familiar in the first place. Is the animal worth spending a season + vis on if it's unremarkable? Is it worth giving up on the possibility to bind another familiar later on? A raven with Might 5 and Int +1 will probably make me go "meh" and walk away. A raven with premonitions, the ability to learn what a dying men saw by plucking out its eyes, that can speak several languages and who is famed for its magic and faerie lore... yeah, that motivates me a lot more on a jerbiton scholar or a quaesitor magus. It's not a familiar I would bring in combat, but I might bring him on adventure anyway. Sometimes it can be about combat stats though. A flambeau hoplite character probably wouldn't care about the raven, but might respect a fire-breathing drake or a wolf that can cause wounds by looking into a person's eyes. On the other hand, a lustful lab rat might be more concerned about having a familiar that can shape change into a human form of the opposite sex and doesn't mind working long hours... Either way, I do expect the animal to be exceptional (in that magi's eyes) or I'll never spend a season to bind it, cute as it may be.
Absolutely!
It bears repeating that Mythic Europe is a dangerous place! Even creatures with Might 20-30 get slain by knights in shining armor or Flambeau magi hunting for vis, or just faeries looking to siphon vitality.
Just because a creature is 'technically' immortal (i.e. ageless) is no guarantee of surviving past tomorrow, or the next day.
I mean, you could just as easily make magi functionally ageless and it would have almost no impact on the game - magi fall to violence or twilight, for the most part. Those are the real threats. For magical creatures, it's violence or acclimation. Becoming a familiar helps with the first and eliminates the second, so it's a good deal for all but the truly powerful ones that don't need it.
Oh, strange, the quote function doesn't seem to work.
Anyway.
Would the scholar fall for the raven, and the warrior for the drake? Maybe.
But I can just as easily see the reverse. It also makes sense in a partnership, since once can complement the other's weaknesses instead of being redundant.
And still, sometimes, you just love someone because she's funny, or a soothing presence, or whatever. Not because she's a world-class athlete (although you can certainly admire her for that, and yes, love that part too).
The point? Well, I guess it's that we can justify just about anything to suit our preferences 
It's instead probably better to concentrate on what familiars can bring to the game, as Troy did.
I believe that it does...
Not for me 
There's a "refresh" circle, and then nothing.
Maybe something to do with navigator/extensions/whatever