at most i alternate between my 4 main characters. noob, reptile, kano, and csz. sometimes i pick a poor matchup (like noob vs smoke) just to try and win
If someone waits to pik there char to try and counter pick me I laugh and hidden select. Or ill start counter picking there counter picks by rotating my 4 mains. I find them to be well rounded enough to have an answer to almost any char. Reptile makes ermac players ragequit
If im playing koth or player and I lose or play ranked tag and I can see I am going against a good opp I will use Smoke. Trying to develop some other characters but Smoke is always my fallback char.
Mostly I use a different character after each match, be it a win or a loss.
But if I sometime feel like truly trying to win I pick Quan Chi.
I guess he is my main, in a sense, I do have the most playing time with him currently.