6 months ago:
Guys... I'm changing my vote to Diamond Tiara. As much as I detest Rarity (and that's a lot), I have realized something: Diamond Tiara is a bucking asshole! At least Rarity gives 1/35th of a shit about her friends. I will trash my previous post and provide an updated list.
4: Flim Flam Brothers (same as before)
3: Rarity (At this point, she beats out Angel)
2: Angel (Nopony treats Spike like a bitch and gets away with it.)
1: Diamond Tiara (Write this character off and millions of bronies will thank you, Hasbro/the writers of MLP. Please. Do it now.)