Frankly, I've gotten to the point where they all annoy me, I'm becoming more and more fond of humano-centric worlds, like Hyboria, and Lankhmar. I'm considering eliminating everything but humans for my next campaign.
Most hated- ducks from Glorantha. I'ma HUGE glorantha fan, but have alaways eliminated ducks in my campaigns.
Most hated-For D&D- the proliferation of "halfies" since 3.x: half fiend, half vampire, half dragon, etc etc. Also the drow ( perfect example of how something very cool can be ruined by absolute overkill..thanks alot UA/2E/FR! )
Likes= as a Kid, elves and Jeff Dee-esque hobbits. Nowadays, dwarves and humans.