I still use emule which was my first venture in serious p2p.
On emule you still find some really rare stuff and what I like of it is it's simplicity in sharing stuff and the centralised search which are the biggest drawback, for me, of torrents.
I mean with torrents you can't move files, rename them or anything that you have to delete the torrent, recheck it, relocate it and so on.
I had to change an hdd recently and man trying to reseed all my torrents is really just cause I am really into the all sharing spirit but is such a pain in the neck.
Also on emule you have an integrated search engine instead of countless trackers you need to sign on, be invited and so on.
Torrents on the other side are more organised so for example of a movie you get all the stats, the thumbs, the covers and so on which is more difficult to do on emule but they have implemented collections and sites similar to trackers for that.
I wish there would be just one single system.