It does have to catch my eye, which means I have to be able to tolerate the animation. And sometimes I just want a random anime with plotless fun, like Lucky Star. I hate most Shoujo art though, sometimes the artists just annoy me with how it looks. Not sure why.
My favorite is probably Yellow, Silver, Red, or Blue (girl, though Green is amusing)
Sure I don't mind And wow really, I thought that was kind of obvious.