I've hardly played it since I got in October, but Cyrax is really cool to me and probably my fave. Sektor, Kung Lao, Liu Kang, Sub Zero and Ermac (mainly ones I remember from MKDA and MKD) I use also.
My favorite character on looks is Nitara, because she is a hot vampire chick, although she is my best character in MKDA, but she is not so great in this game, but I still love her more than anyone else.
My favorite character in Battle and looks is Sareena, because the projectile knives OWN, and her kicks are the shit!