Hands down. I love this site. I was on Elfwood for a while but their submission process is horrible and it tends to be more "kid-friendly"- which is ok if you're worried about that kind of thing. But I'm not.
Epilogue doesn't have much of a sense of community and they're kind of snobby. I've seen some great art on DA where the artist said that Epilogue wouldn't take it. There's some good art on there, but it's just not as much fun.
DA is awesome- fun, a great sense of community, a wide variety of different styles and mediums and subjects. It's a great place to browse art and post your own work.

you said it fanfly ^^
i really enjoy DA
every one's art is amazing
and i have submitied some stuff that got a lot of faves
so I'm pretty happy with this website XD

havent seen the others