I suggest LimeWire or Phex. But, if you want to have the most efficient, fastest connecting, and want serious advanced options i suggest Mutella. It is command-line only, but is very powerful. Only takes a few minutes to learn. Really efficient with your bandwith. Its pretty cool. When i don't feel like messing with the command-line i use LimeWire 1.8c (NO ADS or Spyware in Linux!!!)

Hope that helps...
-Chris