Yeah man, if you main Sub then charecters that work really nice with him are Reptile(since they're so similar), Ermac, Noob, Johnny Cage, Smoke, Quan Chi, Kung Lao, Liu Kang and Sektor. I go back and fourth between Sub and Reptile as mains but now I strcitly use Sub because I haven't used Reptile in so long and its going to feel like learning the charecter all over again. The charecter I use the most as an alt is Johnny Cage but only if I'm absolutely sure Sub can't get the job done. Just started learning Quan Chi and KL the other day and they're really fun to use. Thinking about picking up Raiden too. IMO in this game you want to have a good balance between Rushdown and Zoning Charecters to keep you from becoming one dimensional.