I have to agree with most everyone else and say sore winners. Man, it gets annoying to listen to them, especially their fans. They say things like, "We dominated you" and other things like that. I look at them and say, "Since when were you a member of that team."
I've been on the end of "sore losers" more often than winners. I remember being on youth soccer teams that twice got to the championship only to lose in the end. It's a lot easier to sympathize with sore losers because they had gotten so close and lost it in the end. That makes sore winners even more annoying, pouring salt into the perverbial wounds of the losers, making losers into sore losers.
So yeah, I say sore winners are worse.
Person who has experienced both ends of the spectrum in their life.