Do you mean <a href="http://sourceforge.net/projects/bittorr ... Torrent</a>?
That's good for a single file, but most torrents will die after a week or to.
P2P is more stable, but usually slow / unfair at times.
EDonkey is the fairest of all the P2P networks, what with it's forced sharing and multi-source downloading options. The file you use is chopped up into 8MB segments, as soon as youre done getting one of these segments, it's immediately shared out.
If you like Kazaa, then KazaaLite is the client of choice. With DietK tacked on.
DirectConnect is good for it's indepentant hubs, but it lacks quite a few of the features that EDonkey and Kazaa have. The thing it does have for it is a larger social base, with chat built into the client, people are more social on there and people are more willing to share.
You then have the cold and sterile IRC networks. Which everyone is usually a bitch on, it's a bitch just to get on. When you do get on, you get treated to hundreds of server control codes. Your ip is out in the open. F-Serves are a joke for usablity. I used RenRen's file transfer. Also most of the public channels are full of people with 1 send and 99queue slots on their 128Kbit cable connection.

Bah
>_<
~klinky