Why, because of personal opinions? How about instead of thinking of topics in the eyes of a flamer, you look at the possibilities of conversation?
Two of my least favorite Kamen Riders have always been Den-O and Decade. Den-O, to me, is far too obnoxious in every form, and a spineless wimp as a human. Hell, he's Japan's Jason Biggs in that there is a difference between being nice and being a total pushover. As well, the way the character constantly overshadows everyone else, even other Riders, has always irritated me.
Decade is pompous in a way that gets on my nerves. Kabuto, while sometimes out of hand, always had that more calm personality to go with his ego, and the show normally injected humor into his character. Decade is just a whiny little boy that happens to have awesome powers, but doesn't feel deserving of them. I especially dislike when he rants on why he NEEDS to do what he does, because they always come off as unbelievably self righteous, despite the character's absolute dickery to those that are supposed to be his friends. Even after the Kamen Rider Black story arc, I never at any point felt that Decade actually cared for anyone else other than in forced events.