In the order I played them (roughly):
Holmes Basic: The Tower of Zenopus (this introductory adventure is small, of course, but packs a lot of inspirational material into the space, much of which can be expanded; e.g. the sea cave with the pirates, the evil wizard, the ruined catacombs, et cetera). The "skull mountain" illustration of a sample dungeon cross section, completed with the "domed city" and "the pit." The unique combat rules (Dex-based initiative, etc.) The very OD&D-like stat bonuses and approach to class/race. The strong class-based approach (i.e. no skill system). Actually, Holmes is a very cool little edition. It's even better with the addition of the
Holmes Companion, which expands the levels.
AD&D (1e): The Dungeon Masters Guide -- it has *still* never been equalled. The "successful adventuring" section of the Players Handbook. The original PH cover art, and the "city of brass" art on the back of the DMG. The Tramp, Darlene, and Sutherland interior art. Erol Otus art. Gygaxian prose. 1e will always hold a special place in my gaming affections, and it's still the edition that screams "THIS IS D&D" to me. Still very class-based (i.e. no detailed skill systems, until the NWP stuff was grafted on, but I don't use those). Still a big emphasis on player skill (vs. PC skills). Fast combat; you could run *big* battles with little fuss. Minis optional. Awesome published adventures like the D and G series, S1, S4, the EX series, et cetera.
Classic B/X D&D: A great adaptation or the original game, taking it in a slightly different direction, but still true to the spirit of the older rules. Simpler, cleaner, and an awful lot of game packed into a small package. Classic artwork (both cover and interior). If you want a set of D&D rules that you just "sit down and play" without worrying about lots of complications, interpretations, or house-rules being needed, this is the go-to edition.
AD&D (2e): I liked the HR (historical reference) series of books. And I like
Return to the Tomb of Horrors.
Classic BECM/RC D&D: Very similar to Classic B/X. The Mentzer Basic set is the perfect set for introducing a younger player (especially if you're just giving the game as a gift, rather than bringing the younger player into your group). The War Machine and Siege Machine rules are simple and elegant. The dominion rules are good.
d20/3E: Very nice tactical combat rules when using miniatures. And I love the OGL.
Original D&D (OD&D): At this point in my gaming, OD&D is the perfect edition of D&D. It's very open to interpretation and very easy to house rule/make the game your own. It's strongly class-based, with no added skill systems (indeed, I prefer play with just the original three classes of Fighting Man, Magic User, and Cleric). It's very friendly to the idea of
player skill being important, and
stats are not as important as later editions. There's a huge amount of game packed into three small booklets, but also a range of supplemental material you can add to your game (almost everything that was present in AD&D). You can play it fast and simple, or more detailed and tactical, and the combat system (based on
Chainmail's combat sequence) scales from very
basic and mini-less, to
tactical/mini-based skirmish, all the way up to full-blown mass combat with minis using
Chainmail or
Swords & Spells (men:figure ratios of 20:1 or more). Also, adventures like Tegel Manor and Caverns of Thracia. And the great material in
The Underworld and Wilderness Adventures, spawning campaigns with
underworld mega-dungeons like Castle Greyhawk and wilderness settings like The Wilderlands.
4E: I haven't played this, but have taken a look at the books and read through various sections. Seems to have nice production values and looks like a nicely engineered game system. Rituals are cool.
