This is currently, right, as in, right now? Just 3rd. But I've done all the rest (well, actually I've only read the original books, never played that version).
With the advent of 3e/d20, I've completely abandoned the use of the clunky old 2e ruleset. Sometime I'd like to use my old Rules Cyclopedia for a game or two, but nothing permanent, 3e is king now.
The ruleset I use is d20, but I use sorce material from all editions. They wrote some pretty good things for the earlier editions and I don't mind converting things when needed.
3e, although from time to time I find myself getting nostalgic for some elements of 2e and original dnd. It's not serious though, just the occasional pang...