I highly recommend Pathfinder(http://en.wikipedia.org/wiki/Pathfinder_Roleplaying_Game), it's basically 3.5 with further polishing, 3.5 was released under the open game license and pathfinder has continued it's tradition. It's also got a great support website: http://www.d20pfsrd.com/ and it's really fun. I'm running a Pathfinder game on a weekly basis after about a 5 year break and I'm really enjoying it.
Pathfinder is great. The 3.5e rules really did a great job of maintaining the spirit of the 1e rules, while addressing their many inadequacies. 4e was a real shark-jumping move, but Pathfinder carries the 3.5e goodness on.
It will be interesting to see what 5e is like. Will it be a New Coke/Classic Coke type move? Or Vista/Windows 7... where an obviously flawed product is replaced by something much better that it should have been in the first place?
