I have better luck with Zarya vs Reaper than I do with Hog vs Reaper, I think. Steal his damage, bubble on me, bubble on someone I put between me and him, meanwhile spitting damage at him until he wraiths away. Follow him and burn the rest.
a lot of dmg from close range + his spread is very fit if you're battling heroes with bigger hitboxes, which makes reaper deal like around 200 dmg if u get a headshot on a tank like winston.