Gen 1 and 2 are the best because
1. The pacing, running shoes killed the journey
2. at the time of release, these games (especially gen 2) really showed what the original gameboy can do, this gameplay is archaic now and should have been updated for consoles (a real console adventure)
3. The artstyle (no, not the designs, which i'll argue to the death but is ultimately subjective, I mean the artstyle was better)
4. actually evil bad guys, who were TERRORISTS
5. No chosen one bullshit, the point is to be a pokemon master
6. Gambling for pokemon, Pokemon tower, those pokedex descriptions, everything felt more serious and real and less like the anime, more like the manga
7. Rival who is an actual douchebag that you want to beat
8. no fucking wifi trade center ruining the point