I just need to stick to what works. I started this season at 1450 SR and just now reached 2000 using Reaper almost exclusively the last 200 points or so. I've won nearly every game consistently, my last one being on Oasis and going 55-2, with golds in eliminations, objective kills, and damage.
There's something to say about being proficient with other heroes, and I do switch to another player on defense (usually Roadhog, Sym, Mercy, or Lucio), but damn, when it works it works and I should just stick to it.
Anyone else resist their top characters for a while for no good reason? I'm busting my ass trying to have good games with Genji and Pharah and Sombra and here I am nonchalantly shredding the other team with Reaper. To the point it feels cheap. Reaper is an absolute MONSTER. I don't know about the highest levels of the game, but I don't think a lot of players at my SR know how to handle an extremely aggressive, balls-to-the-wall Reaper that doesn't respect the enemy's personal space. lol