This is a tough one because so many of the classes are fun:
Adept - Batarian w/Graal Soldier - Original Turian w/pretty much any automatic weapon Engineer- Geth Sentinel - Paladin Infiltrator - Salarian for sniping/Geth for shotguns Vanguard - Krogan --- We're here! We play Pokemon! Get used to it!
Adept - Justicar Soldier - Human Engineer- Salarian(oh yeah, still rock him) Sentinel - Turian Infiltrator - Shadow Vanguard - Manguard --- British people have the accents. Not Americans. I can prove it.