Despite its detractors, I firmly believe that FFXII had an understated cast. Characters felt like real people and didn't spend every other cutscene telegraphing their emotions. They had nuances to them that were evidently lost on some people. Oh, and ofc, a lot of fans were let down by the lack of swashbuckling romance.
And yeah, maybe Vaan wasn't the most compelling protagonist in FF history, but I'd sooner take the naive everyman over frickin' Squall.
Anyway, fave character:
I'll be a total whore and say Balthier. Yes, he's suave, irresistible and dapper and all that jazz. Nevertheless, there's more to him than those superficial qualities. He's the de facto leader of the party, with worldly experience beyond his years, providing the gang with valuable insight and candour. And there's a touch of pathos with his strained relationship with his father, the eccentric Dr. Cid. I think their final exchange said much more than any 'NOOOO FATHER! LUVVV MEEEE!' baww that probably would've happened if this was another FF.
I also enjoy Basch for being, what I find to be, a deconstruction of the archetypal white knight. Basch finds himself disgraced by Vayne's machinations and has to win back the trust of his kingdom, namely Ashe. Even when Basch does inevitably reclaim his honour to Dalmasca, he must face his own personal demons. While he may have left Landis with good intentions, he nevertheless abandoned his family and left his brother for the clutches of the Empire. Yet Basch makes no apology for this, for he has learned to accept the consequences of his actions, come what may. However, the least he can do for his brother is fulfil his dying wish.
Then, of course, there's Gabranth, a character who
cannot let go of his past. A lot of the angst towards his brother is actually the projection of his own failings. He convinces himself that what he's doing (being the Empire's bloodhound, dancing to Vayne's tune) is justice and somehow vindicates his own betrayal. However, during the game, we watch Gabranth carefully unhinge until he finally cracks, realizing the error of his ways and spending what life he has left to protect Larsa.
Also: Fran, Vayne, Dr. Cid, Vossler, Larsa, Reddas, and that hot pirate chick in Balfonheim.