1) Burst - http://krypt.dyndns.org:81/torrent
2) PTC - http://ptc.sourceforge.net
3) Azureus Java Client - http://sourceforge.net/projects/azureus/
4) The SHAD0W's EXPERIMENTAL S-5.2.1 - http://bt.degreez.net/
Explain whey you think its the bast ...
Edit: add a link to the BitTorrent-experimental-S-5.2 site ...