The first RPG I ever ran was Dungeons & Dragons, Third Edition. I wasn't nearly as tied into gaming news then as I am now. No one was, though I certainly could have been more informed — if I knew ENWorld (or its predecessor) existed, for example. But I was aware that a new edition of D&D was coming out, probably because I collected GURPS and other game books and was no stranger to a hobby shop.
In the fall of 2000, I picked up the three core rulebooks for Third Edition. The Player's Handbook came with a CD-ROM — remember those? — with a character creation program. The first adventure I ran was a bizarre affair involving an abandoned wizard's tower surrounded by a village of lawn gnomes, with a dungeon beneath inhabited by a cotton candy-pink dragon. Keep in mind, I was a senior in high school at the time. And I've never done drugs.
Anyway, I was hooked. I managed to play in a campaign through graduation, and then when I got to college, I joined the gaming club as soon as I could. There was only one other D&D game going on at that time. Of course I joined, but I also realized there was room for another DM to run a game. I started running D&D every week, and I basically didn't stop for the next five years.
During that period, D&D added a period of its own in the form of the 3.5 revisions. I pretty universally agreed with the changes made to the game and incorporated the new version as soon as I got back to school in the fall. I ran games in Ravenloft, Eberron, Krynn, and a long-running game in a homebrew setting I built on the fly. I ran a game using Oriental Adventures that ended closer to a TPK than I've ever come before or since.
I kept running 3.5 after I graduated and entered the "real world." More games in Eberron and Dragonlance. An Expedition to Castle Ravenloft. And I played in the longest-running campaign of my gaming career in a friend's 3.5 version of Kingdoms of Kalamar.
Measured in hours, die rolls, and International Smile Units, Third Edition has given me more joy than probably any other roleplaying game. I would gladly run it again any time. In fact, I'm thinking about doing just that in the near future, delving into the mega-dungeon of Goodman Games' Castle Whiterock.
Dungeons & Dragaons, v. 3.5, is one of my Favorite Games Ever.