1) Dio was just a generational hater.
2) Kars just wanted to dominate the planet.
3) Kira was a literal psychopath serial killer. Nothing justifiable.
4) Diavolo was trying to maintain his identity by killing his daughter, which is understandable but I believe he didn't deserve a whole death loop over it.
I'd say Funny Valentine was the most reasonable. He just wanted to make America the greatest nation and was willing to do anything for the country. It was just that his methods were pretty brutal (murder, manipulation, etc).
I'd say his motive wasn't selfish at all
