I would have to say action with a good story. Like Canaan and Darker Than Black (both amazing series). To the me the story is usually what matters the most, like Steins;Gate, not a huge amount of action, but a really interesting and well thought out story.
Definitely horror. Too bad Japan isn't really good at that with anime, only the first season of Higurashi had me a bit unsettled. Shiki was fun to watch, but it wasn't really freaky or scary or anything.
To be honest, I like action packed anime more than anything... as long as its entertaining... but nothing beats a good laughter either like angel beats or soul eater.. action-comedy anime rules..
im a mecha man all the way ^^ and while evangelion will ALWAYS be my favriot overall, in the genral of mechas its a close tie between eva, gundam 00 and gundam seed. the story behinde them just strikes a chord with me, peculiarly 00 and seed, the storys they tell are that of the darkness of humanity and how we can overcome that darkness.