AT's biggest crime?

[Fantastische Hure]

This person has committed countless atrocities in the world of manga/anime.

Green-lighting DragonBall Evolution
DragonBall Super
Being the reason for Bleach's existence

Which is the worst?

 

[Captain Cadaver]

Probably Super. Toriyama at least expressed disdain for DBE and made BoG out of dissatisfaction with it, so he's not fully to blame for that (especially when the director said he knew nothing about Dragon Ball iirc).

Being the reason for Bleach's existence

Togashi and Kurumada are more to blame for that if anything, given their respective works Yu Yu Hakusho and Saint Seiya were far more influential on Bleach than DB was.
You could say Toriyama had some vicarious role due to YYH taking chunks of inspiration from DB, though the same can't be said of Saint Seiya.

 

[Papasmurf]

AT wrote an encouragement letter to Kubo after Bleach was initially turned down for being a YYH clone, and post-Soul Society Bleach is basically just as bad as Evolution.

Can't say for sure, honestly. I'd say Super is his biggest crime also as it's still ongoing in manga form (and the anime will start up again soon), and he OK's Toyotaro's atrociously inconsistent and incompetently written chapters.

 

[Captain Cadaver]

Ah, didn't know that. Still, an encouragement letter is still far from a recommendation letter and is overall not much of an active support of the series (and the first arc of Bleach still has more going for it than most of Super and 2010s Shonen in general, at least).