3.5.
It is expansive and creative. At times a challenge to DM, but also preserves well the best parts of the feel of D&D. The splat books get a bit hairy.
I gave 4th a chance, but I agree that it tries to do what computer games do, when it should be trying to bring out imagination and choice. 4th goes partway toward, but falls short of, embracing some important contemporary RPG design (which is often now better found in Indie games). Maybe 5th will be better, or even 4.5 (4th essentials) might drift it a bit closer to good. Is that likely? 4th is a bit munchkinny (some 3rd splatbooks are *very* munchkinny!)