I haven't done competitive yet myself. Given there's so many characters I do have characters I have played more than others and that I'm better at than others, but I do like playing a variety if team comp allows it.
Out of just quick play though, my top 5 characters are
Soldier:76
Mercy
Mei
D.VA
Orisa

All Modes is pretty much the same except Lucio takes Orisa's place, with her playtime being just below him. Junkrat is just below them in both lists. In reality I have played more of both Lucio and Mei than this shows though as I used to play on my partner's account before I bought it for my computer and I used to play those two quite a bit. I also play at least one match a month that I record where other people choose who I play so that mixes it up too. So far I have been letting patrons decide but that's been literally only my partner as he's my one patron so after the video I'm currently editing I'm opening the voting up to everyone. My partner thought it was quite funny to make me play Doomfist the first time I did this.