Tedou Pompous but not really that much of a jerk. I like to think of him as a kid who just thinks the world revolves around him and not realize that it really doesn't.
Yuuto was more of a how shall we say a mask, he wasn't a jerk he just didn't want people to get close to him since well people forget him every time he transforms and how would you feel trying to make people remember you all the time. He was lonely and just didn't know how to deal with people since well why deal with people who would forget you the next day ?
Keisuke, is well he's a lot like Rorschach from watchmen he has no gray area in which to adjust his morals too. He dosn't take the time to sit down and think in many ways he is basically an id, not really thinking things through and sitting down to think. Heck the fact that he can accept Wateru as Kiva maybe shows that if he knows someone is good he backs down. He basically a look at the toku hero who just fight the monster and never get to know that they are actually good people caught in cruel circumstances.