My top ten would probably be (including past characters):
1) Brienne
2) Varys
3) Cersei (obviously a bitch but god damnit a fierce one)
4) Tyrion
5) Arya
6) Ned
7) Tywin
8) Jaqen (even if he's been a bit crap this season)
9) Bronn
10) Oberyn
I'd like to say I'd include Syrio Forel but it was just too brief really to be taken seriously
and The Hound, Jorah, Jon and Margaery come close.