I thought that RuneQuest 2 was preferable to AD&D (1e - the last edition I played). RQ3 had some clunky bits, and the current (Mongoose) incarnation is probably between 2nd and 3rd editions on that score. RuneQuest doesn't have the same sort of powerr progression as D&D had, though.
(Mongoose RQ has been OGL'ed so there are SRDs available off
this page) And if you've played any of the BRP games, like Call of Cthulhu RuneQuest should be fairly familiar (BRP started as a simplified RuneQuest).
Of course, D&D has had two huge revamps, while RuneQuest is still largely the same game as it was when it was first published in 1978.