I have to agree with sake. When I really want a particular movie, I look around at all of the sites that have been mentioned again and again, If I still can't find my movie- I look at Zamunda and Demonoid. There may, or may not, be a lot of seeds- and it may not dl in 7 minutes, but these two rarely let me down when I need them. Purely for content, though.
As for knowledgeable community, interesting discussions, recommendations of the movie I am now hunting for, and being able to find packs with specific directors, etc. These two are no good at all.
I am curious how "packs" will change and/or improve torrent site retention. The siTe(S) that are (re)structuring around these packs seem to be doing a nice job!