He's got a strong case. Draining Galdino until he's a husk and feeding him live to a bananagator remains one of the most fucked up murder attempts in One Piece.
Not to mention how much joy he took in stoking a rebellion. Edit: which
@ZenZu posted panels of.
The young master and croco boy are among my favorite characters in the manga because they are so damned depraved.
They cause large scale suffering, for their personal gain, and take pleasure in it.
Enel is similar. Honestly lucid linlin is not far off, what with sending severed heads as wedding invitations and the whole scheme with germa. Lucci is stone cold but not at their level.
Kaido is too one dimensional for me to view in a similar light.
And I maintain Akainu is ruthless, but not at anywhere near the level of evil of this bunch, rather he’s an answer to them.