I'm a fan of AD&D 2e. It's what was current when I started playing, and I've pored over those books with an intensity only a dorky teenager can muster. The last game I ran was a several-year-long 2e campaign. It's the edition/system I know best, and running it is second nature to me. I typically run homebrewed settings, but I love the diversity of settings published for 2e: Planescape, Dark Sun, and the like really showed how far 2e could be pushed.
The only problem I have with 2e is that my wife did NOT enjoy the system. I'll likely have to figure something else out when I run another game because given the choice between her and 2e, I'm going to go with my wife.