I think it makes sense that many top players used to differentiate their tierlist between tournament ft 2 setting and long sets, saying that, a S Tier character should be good at both, imo. Having moves with low risk and high reward, covering multiple properties in a single move, helps for sure. Rewarding punishment options as well. (i10/i11 launcher☠) I can also see the advantage of having a simple gameplan and easy execution, which let's you focus more on the basics. This could explain why Gigas often does well in tournaments, at least in Asia. But on the other hand, comeback factor is also something that should be considered and some characters excel at that.

i think negan is underrated tournament character

Solid neutral, poke game, small tekken and atleast average movement