Easy answer for me. Brotherhood. While they had their good moments in the original, Ed and Al practically ruined it for me, whereas, in Brotherhood, they are far more enjoyable.
If Ed and Al were tolerable in the original this would definately be a harder decision because everything and everyone else in the original was really good.
USF4/SSF4AE2012 - Yun
SFxT - Dudley, Cody, Ken, Jin, Kazyua, Ryu, Asuka, Hwoarang, Steve
GGXXAC+R - Johnny, Sol Badguy, Order-Sol
BBCP - Hakumen, Hazama, Jin
P4A - Akihiko
3S - Dudley, Ken, Ryu, Yun, Yang, Makoto