I've been playing 2nd edition with a few house rules since '92. Through NWN 1 and 2 I've got a glimpse of 3/3.5. I truly like the skill-system in these editions but couldn't convince myself to buy anything of them.
2nd Edition, full Player's option rulesets with a few house rules borrowed and converted from 3.5.. combat & tactics has the best combat rules for D&D bar none which is why my group still roll with it..
Some of the most awesome epic battles I've ever played have arisen from this system.
I play 3.5. it's streamlined, allowing almost anything to be played(as a player or dm). combat moves smoothly, and all classes are skilled differently. I'm not impressed with what i'm hearing of 4e, both rule wise and lore wise.
"The measure of an undisciplined mind, is that the intellect allows emotion to challenge the observed truth" Richard Baker