>>29704871Gen 1.
Gen 2 is my favorite, although I lump the gameboy games together. I loved the connectivity with Pokemon Stadium 2, the two regions, and all obscure features it added.
I'll admit some of it is nostalgia.
A lot of the new Pokemon were extremely rare, mediocre, hard to obtain with specific events/trading, or just distributed poorly throughout the games. Even still I think it made finding them more interesting.
Finding events without internet really special, the time and day system seemed so revolutionary. Throw in the show and all the spin-off games like Pokemon Snap and there was an environment I don't think you can really create now replaying the games.