Rena from Higurashi.
I'm sorry, but she turned me off in episode fucking ONE.
Other than that, I would say Esther from Trinity Blood.
Lynn Kaifuun from Macross ALMOST counts, but it was fun to watch his drunken debauchery in the post-apocalypse, even if he was the world's most annoying pretty-boy Chinese hippie in the pre-apocalypse. (DISCLAIMER: I am a liberal. But I still loved seeing that little bastard squirm.)
I didn't hate Rossiu. I thought the poor guy was a perfectly reasonable and important counterpoint to the GARness of Simon and company. Without him, the GARness would have gotten really stale, really fast. Oh wow, you're all pumped to fight the Anti-Spirals. Wow. So is everybody else in this fucking show. You're not special in the slightest. SOMEBODY has to be the Felix to your Oscar, and it may as well be Big Ross.