Shadowrun is definitely top of the list, SR3 to be precise. I'm currently GMing a low powered, sort of apocalyptic zombie campaign using SR3 rules. I'm a big fan of Fading Suns too, very similar feel to Freelancer. While I've played my fair share of DnD, I'm not a big fan because it is very powergamey and combat focused. Apart from that, mostly the usuals like various WoD, MERP, various GW ones (WHFRP in particular) etc.