I'm using from time to time Shareaza and i'm happy with it. Tried once Limewire, Kazaa and Bearshare, but they sucks for me, especially when i got unwanted adware problems. When using Shareaza, you have to be carefull using the right version, as there are 2 versions still existing. The one and only real Shareaza is available through the open source network portal Sourceforge. Once there was also a direct website, donated by a French guy but at a certain moment he got lots of trouble with French law (illegal downloading/uploading issues) and he had to get rid of that website (it was registered under his name) and unwanted it became property of an commercial American party. (bearshare??)
Shareaza works with Gnutella, Gnutella2, Edonkey (Ed2k) and Bittorrents, but if anyone has suggestions for other networks and clients, i may try those.