Tank: Orisa. Some of her problems could be eased with a support or two or a tank buddy that works well with her… but… literally no one is scared of just waltzing through her shield.
To the end of addressing that… I suggest buffing her quick melee to 50 damage and using Fortify buffs it to 70. Make it so people don’t just waltz through her shield because there’s a 70 DPs metal knuckle sandwich waiting for them on the other side.
Support: Mercy. I have numerous problems with her and numerous potential changes/reworks.
Damage:
I… should probably say Doomfist. Problem is that I don’t really want a semi tanky, very mobile, 1 shot machine to be viable.
In lieu of that: Soldier. He’s not… bad per se. He just doesn’t really have a reason to be picked over the rest of the DPs Cast. In my opinion the way to buff him into at least semi relevance is to nudge him towards being a DPS who’s sorta also an off healer. So buff Bio Field from 5m radius to 10 or 12, and reduce the CD from 15 to 12.
Other DPS is probably Reaper. Reaper does not need 50% life steal, he needs his E to be redesigned. Still have it do a similar thing but make it not the most clunky ability in the game.