My top 5:
Earthdawn
Shadowrun
oWoD (Especially Vampire & Mage)
Fireborn
Warhammer
Other games I have played:
Call of Cthulhu, Exalted, Paladium Fantasy, Rifts, GURPS, D&D 1st., AD&D 2nd. D&D 3rd., Drakar och Demoner (Sweedish system), Fusion (Danish System), Ars Magica, SLA (haven't played it much but love the setting), In Nomine, Cult, Starwars D6, Starwars D20, TORG, Amber, Tales, Viking (Danish system), Rolemaster, Paranoia, Serenity, Star Trek, Talislanta, Via Prudensia (Danish System) and probably some I have forgotten down the road.
Regards
Rasmus