If you want a revenge story, Nidome no Yuusha is the best. It starts off feeling a bit over edgy, but as it fleshes out it earns it. Although it's a bit over the top in having all the high ranking people be so trash behind their masks.
I got to disagree with
@Chrona assessment of this story vs
Kaifuku Jutsushi no Yarinaoshi. While I do agree the mange version hasn't really give as much backstory for the revenge in Nidome no Yuusha, I do think it will be fleshed out more in the future. It's really just setting things up now.
If you go by the novels, then Nidome no Yuusha wins hands down. It really rolls around and indulges in the revenge. In the second volume 2/3 of the book is setting up the revenge and 1/3 is carrying it out. In Kaifuku Jutsushi no Yarinaoshi MC-kun's revenges feel really incidental. While I do like his sociopathic personality, he really only has 3 people that are a target for revenge. And 2 of them were done in about 2 chapters in 8 volumes (with the 3rd not yet complete). While you feel a touch of his madness from time to time it's not really as ever present as it feels in the main characters of Nidome no Yuusha (they're ALL crazy, this is a plus).
Any way, the MC in Nidome no Yuusha reason for being
IS revenge. It's what the whole story revolves around. In Kaifuku Jutsushi no Yarinaoshi revenge is just something the MC wants to cross off his list. It feels incidental to the main story.
Oh and
@SovietWeeb the whole point of the poison food was to induce psychological suffering. Even knowing the food would turn them into a goblin they couldn't keep themselves from eating it. I don't see how this could lead to a plot hole. She can make unique poisons that have unique effects. So far there hasn't been a case where a reader would ask "Why doesn't she just use that poison she used before?".