Honestly? B/X is raw fantasy. It’s fantasy before it was codified by the rules of AD&D, by the publishers, by players, and by us geeks. Do you like He-Man? Do you like Beastmaster? Do you like Lord of the Rings and The Hobbit? Do you like Gummy Bears? Dragon’s Lair? Recluse and Vance? Space wizards vs knights? Delving into deep tombs or exploring ancient ruins? The actual D&D cartoon, or Thundar the Barbarian? All that is included within B/X’s broad umbrella. Whereas Gygax seemed to want to adapt a medieval world to fantasy with Greyhawk, B/X embraces the weirdness of the fantasy genre as it existed prior to, say, 1988, and runs with it. Owlbears, for example, don’t need an ecology; they are aberrations, magically created beings. They don’t fit into the world because of just that. They are WEIRD. You want to have characters where they players define how they fit into the world? B/X is your jam. Characters aren’t solely defined by their classes, but how they are played, and how they approach problems. Classes are so broad and nonspecific that they cover so many concepts, and it that goal of being archetypal.
I dunno. A few of the points I made above can be done with other editions. I just don’t think any other edition (or fantasy game, to be honest) hits them all at once. B/X does. The level range, while weird for us modern thinkers, works perfectly. Vancian casting actually has meaning, in that you have to search out spells and bargain. It’s not murder hobo, as you want to be efficient. Weirdness is there, without any attempt at being banal or common. Exception-based design means you can change one system without detrimentally affecting other systems. Ability scores make far more sense.
Sure, you have races-as-classes, but that WORKS. Apart from Drizzt, how often is the main character of a story series a nonhuman? When you encounter a dwarf, they are a DWARF; they fight just as good as fighters, but are tougher. Elves? Elves are WEIRD. They can fight AND cast spells.
I don’t know if the above makes sense to anyone but me, but one thing that I love about B/X is it’s unapologetic embrace of all the incongruities and imbalances of a fantasy world where things from folk lore, science fiction, adventure fiction, and common sense come together.
B/X is Weird Fiction. If that’s not your thing, best to ignore it. However, its broad pedigree gives it a flexibility that is unrivaled amongst TTRPGs, and lends extraordinary credence to its viability as a universal OSR translation system.
Edit to add: I started with 2e, and that’s still my favorite edition. Im currently playing in a 5e campaign, and have spent a ridiculous amount of money on it. That said, B/X is THE gold standard for me. Nothing else really approaches it IMHO.