Well, most of you probably going to hate me but,
My favourites are
Littelfinger: He keeps basically everything in motion. He simply cant be blamed, he ask you to don't trust hib, and if you do, it's your problem. He keeps everyone in total gloom. He does the most unpredictable things -you'll see in season 4- without any practicular reason, and keeps his foes in gloom. A bloody genius, this one.
Roose Bolton: He's a real cold whoreson, he simply swept down his soon-to-be rivals with a clever allegiance, and a calm smile on his face.
Dolorous Edd: His sarcastic black humour is just awesome.
Bronn: Surplysingly good strategist and animator for a mercenary, and he keeps everyone aware, that hes only loyal to the coin, which I call good sense
And you just going to hate me more but:
Well, the least favourites for me are the older starks (the younger ones have promise tough: Arya is a crazy whoreson, Bran is aware that he is a warg, how badass is that, and rickon... well, he's only 'bout five.)
Eddard has a stick in his ass, called honour
Catelyn can't accept his Husband's misstep, and she blames it on Jon.
and Robb's just a younger clone of Eddard, with even less Character
also, Stannis is as stubborn as a rock, wich is not necessarily a good thing, but if it's comes with leaving his senses, then he's only an annoyance.