Dungeons and Dragons has united millions of players since launch, forging long-lasting friendships - and of course, ruining some. There have been many iterations of the tabletop game throughout its roughly 40-year lifespan, so the game has changed quite a bit since its inception. Of course, not all editions are created equal, and some are considered far better than others by the player base.
7 4th Edition
Ask any member of the Dungeons and Dragons community what the worst edition of the game is, and they'll almost certainly respond with 4e. There's quite a bit wrong with 4e, mostly stemming from issues with classes in the version. It's difficult to make a unique character. Plus, it's more combat-centric, which is great for some players, but not those that would prefer to spend their time role-playing. All in all, 4e felt more like a tactical combat experience than it did a full-fledged Tabletop RPG.
6 Advanced Dungeons and Dragons
Advanced Dungeons and Dragons is where the game as we know it began to come into its own. It laid down the groundwork for everything D&D would grow to become, separating itself from the basic Red Box kit from a few years earlier. That being said, it was also incredibly dense. For those that are new to the game, learning its rules will take quite a bit of pouring over. Gary Gygax's writing style simply isn't as easy to digest as newer versions of the game, and it's definitely noticeable.
5 Original Dungeons and Dragons
The first edition of Dungeons and Dragons was incredibly basic, offering just three classes: Fighting-Men, Cleric, and Magic-User. However, it's impossible to downplay the cultural importance of it, as it would go on to have a ripple effect on nerd culture as a whole - forever changing novels, movies, and video games. It may not be the best edition that Dungeons and Dragons has to offer, but it's definitely one of the most important.
4 Second Edition
Second Edition came with plenty of improvements over Advanced Dungeons and Dragons, mostly in how easy to digest the actual rules were. All around, the game became much easier to understand and fixed many flaws of the initial version. For people that have been playing D&D for decades, there's also a nostalgia factor, as Second Edition is where many got their start in the world of tabletop role-playing. It still has some problems, but it was definitely an improvement over the prior version.
3 3rd Edition
Wizards of the Coast took over with 3e, and the changes were noticeable. It removed a game mechanic called To Hit Armor Class 0, or THAC0, which, without delving into the specifics, made math in the game a bit more complicated than it needed to be. While this edition still has some balance issues, it allowed players to make characters that were a bit more mechanically complex, which added a lot of depth to gameplay at large. However, it would go on to be overshadowed by its little brother, though it still set a pretty high bar for the future of the game.
2 3.5 Edition
As far as Dungeons and Dragons editions go, 3.5 has very few flaws. For many, it's the best edition of the game, offering a pure role-playing experience and a multitude of big improvements over the standard 3.0 version. It's also partly responsible for the invention of Pathfinder, an offspring of Dungeons and Dragons that many argue is better, in some ways. That being said, some players have found way to over-optimize the game with certain character builds, which can eliminate a lot of the fun. Still, there's a reason so many players still use it to this day; it's genuinely excellent.
1 5th Edition
It's hard to measure how much Dungeons and Dragons has evolved as a hobby over the past few decades, but 5e is a testament to decades of work. It offers up a grounded experience, where 3.5e allows players to go just a little bit more crazy with their rolls. But at a deeper level, 5e has been behind the renaissance the Dungeons and Dragons has experienced over the past five years. It's been the kick-off point for millions of people discovering tabletop gaming as a hobby for the very first time - and there's something truly special about that. 5e, from both a gameplay and a cultural perspective, is D&D at its peak, and it will be very interesting to see what the future holds for the game.
Dungeons and Dragons has steadily improved over time in a way not many other games, or anything, for that matter, has. It's had a profound effect on nerd culture, and that doesn't seem likely to change. It's gone on to unite players behind a shared passion, becoming something millions of people can use to bond with each other and form legitimate human connections. It's hard to say just how special this game is for so many people, but it's been absolutely wonderful to watch it evolve over time.