Total jerks with broken hearts. I don't know why I keep returning to that kind of character whenever I start a story. I simply find them... pitiable? I wish them to change.
Sometimes, that'll only happen for a single moment before everything gets ripped away from them. Is there ever a happy ending for these guys? You tell me.
I also like writing crazy goofballs with REALLY compelling backstories. They'll never be the main character, though, as the universe couldn't bear the weight of their antics.
One more character type I really love: friendly friends. Not the "tease you 'till' you die" type, but the "I'll tease you because I know you can take it" type.