Thanks man, Yeah ever since I hit diamond League (3400 Asia server; in America I would easily be Masters i believe, the Koreans are WAY better than we are overall) I only play Mystery Heroes if I'm not playing Comp. My goal is to be as good as I can with literally every character to the point where I don't care who I play. I am very happy that I feel natural with Sigma, and I think he even might be OP at the moment, at least vs. the players I play against which are often Koreans that are actually playing professional / on television in Seoul.
Brigitte has been my biggest problem forever, but after the recent huge and major change to her, I understand her completely and I finally am doing well with her. I don't have fun with her but at least I can play quite well.
Bastion is definitely one of my weakest characters, but in low stakes games like Mystery Heroes, I tend to not try as hard as usual, and I just thought the music matching up with the game was funny.