Evan Though she was only there for the first few months its still Jemma Jay for me. She always performs the best she is allowed.
seems a bit futile having quickly looked through the rest of the votes but if I had to choose just one it can only be Emily Dean for me
Edit: having since found out the amazing Ms. Dean has sadly left Bang I'll have to change my vote... I would say Jet as my next choice but I've not seen her in a long while so based purely on the impact she's made in such a short space of time I'll have to say Kerry Louise gets my vote.