Of course I love all the parks but EPCOT has always been my favorite because it's more spread out so the crowds aren't usually piled up in one place. Plus I'm a nerd and I've always liked the educational stuff (even on my first trip when I was 7 LOL).
The older I get, the more I lean towards Animal Kingdom. Not necessarily for the attractions, but more for the animals. The DW and I have always been a fan of the Big Cats, and they do have some magnificent creatures there. As far as the rides, I would have to say DHS, because I can't go to Disney without getting my ToT, and RNRC fix.