I'm personally a picky anime enthusiast...I hate Gundam (and pretty much all mechas in general besides Full Metal Panic), I hate Dragonball Z, I hate love triangles, I hate most shoujo, I hate plots based around a nerdy guy suddenly getting a harem, I hate emo protagonists, I hate stories that are completely based on characters fighting, and the main character will always get his ass kicked until he somehow finds some new power and defeats the enemy, I hate stories that revolve around some guy finally meeting up with some lost love, only for it to be ruined by other girls who coincedentally fall for him at the same time, and I could go on and on...Oh yeah, sad endings! Sad endings make me angry...Angry with rage!
I tend to like anime with either deeper stories (Mushishi, Kanon, Miyazaki) or random, unique comedy (Suzumiya Haruhi, Hayate the Combat Butler, Sumomomo)...