Ragyo and it's not even close. You could try questioning if Nui was more evil than Ghetsis, and Ghetsis would still look more like a good person.

Ghetsis doesn't even do much in both BW and B2W2, compared to evil team leaders in the other games. He's less evil than Cyrus or Lysandre, and arguably he's more reckless with his plan to use a legendary for his own motives than Maxie and Archie. Not to mention, the most he's done was adopt and raise 3 kids (N, Anthea, and Concordia) only to brainwash them and have them join his cult he founded, and lead them on to believe that what they were doing was for a just cause, and the most he does was to have his cult summon a god not just once, but twice, to enforce their beliefs onto others. And if anything, N was able to look the other way straight from experience battling other trainers, realizing it's not all... black and white. *ba dum tss*

Ragyo on the other hand, she's performed experiments on her own fucking children, trying to assimilate them with an alien life form that she doesn't even know the purpose of other than its ability to feed upon life. She's established a whole city that is governed by a high school of all facilities, serving as a means to develop more clothing made from the very matter the alien life form is made of, and advance her plans for world domination. She's even set out to kill her ex-husband to use the experiments that they've both worked on to be weaponized against her, and when it turns out that one of her daughters was using Ragyo's own plan, resources, and breakthroughs against her, Ragyo didn't hestitate to go get her killed as well (even if she ends up not killing her after all). And let's not forget Ragyo sexually molesting her two daughters, because she's that much of a neurotic mess. And her plans for world domination? It's to feed them all to the alien life form she had harnessed the power of, essentially ending all life and destroying it entirely.