Well, I have to say, I've loved dnd since the Basic Set.
I loved 1e and 2e, thought that a lot of the Players' Option book stuff sucked but some was great, and converted faster than a peasant with a sword at my throat before 3e was even out.
I'd play a one-shot in another system, but I really think that 3e is so much better, so much more of a unified system, so much more user-friendly, that I'll never go back.
And while I'd be willing to play a 2e game again for a session or two, the dm would HAVE to use the 1e dmg. There was NO excuse for the 2e dmg- reprinted sections of the PH and a few dozen pages of magic items. Ugh!
But, generally, all the different incarnations have their strengths and weaknesses.
OD&D has, as its greatest strength, simplicity. It's easy to learn, easy to play. It lacks rules to cover a lot of situations, but a lot of people like that. A lot of dms like making on-the-fly rulings and don't worry about the inconsistencies that can develope, or else they take the copious notes necessary to make sure that they keep the rulings consistent. I'm not that organized, personally. Think of OD&D as a simple sugar cookie.
1e has, at its greates strength, complexity. There's a rule for almost everything if you look hard enough through the Dungeoneer's Survival Guide, Wilderness Survival Guide, Oriental Adventures, etc. But the rules don't always fit together as a whole, and when you add in the stuff from Unearthed Arcana all balance gets thrown out the window. 1e is like a chocolate chip cookie with a hint of vanilla, walnuts, cashews. a salty crust and bits of chocolate-covered coffee beans crushed up. There's lots of stuff, but not much actual cookie.
2e has, as its greatest strength, a sort of strange mixture of simplification of the 1e rules, complexification of the 1e rules, kewl settings, and lots of resources. There's a complete book of everything, although halflings and gnomes somehow got lumped together. The only thing that I personally liked better in any old edition than in 3e is the way cleric spells worked, with spheres and all that. 2e's greatest weakness is that, with all those books, there are a lot of contradictions, imbalances and silly things. I mean, come on, look at kits; look at the way generic clerics are totally flavorless, making the whole specialty priest thing useless unless you go to the effort to work them up; look at the official specialty priests and how unbalanced they tended to be. Worse still are the words tanar'ri and baatezu. What?? 2e lacks flavor at its base- you can stick it back in but it requires a lot of hard work. It's like a chocolate chip cookie with nutrasweet instead of sugar.
2.8e (by which I mean the PO series) has, as its greatest strength, the most customizable system available before 3e. But the negative side of this is that it's a power gamer's wet dream. In fact, there are things in the Skills and Powers book that make it impossible to make a standard PH fighter- you've got too many points! Not to mention that humans suddenly power up, and you can build a cleric who has everything a fighter has plus spells. Again, balance gets defenstrated. It's like a batch of cookies that has everything somewhere in the batch, but some have chocolate chips and walnuts, some have m&ms, some have white chocolate chips, m&ms, walnuts and popcorn, for that matter, and some are just plain.
Then comes 3e. Demons and devils are back; the flavor of 1e has returned. The rules are comprehensible and encompassing without being a strange Frankenstein's monster of different systems. There is a core mechanic that is easy to use, understand and apply. There is a tremendous amount of work that went into balancing things, at least in the core rules. 3e takes the best of all the systems- the simplicity of OD&D, the complexity and flavor of 1e, a great deal of the customizability of 2.8 and the sphere system (although not quite all of it)- and cooks it into a wonderful wonderful cookie that's got the chocolate chips, walnuts, real sugar, and macadamias in it.
Just my humble opinion, of course.
Just my opinion.