My favourite generation is the one I have nostalgia for and the first one i played, Gen 3
Ruby and Sapphire i think had really good pokemon designs especially my favourite legendary Groudon, he looked metal as fuck on my copy of Ruby. I enjoyed the soundtrack from the GBA version and matched the anime based from it, Pokemon Advance.
What is your favourite generation and why? What details makes it stand out for you?
Gen 1 had a lot of design issues: The special stat is overpowered, too many pokemon were poison type, move diversity was so poor that some types were just useless, and there were a lot of glitches.
Recent generations also have design issues: The story holds your hand every step of the way, characters are more detailed but less expressive, each generation has a gimmick that gets abandoned in the very next game, and there’s somehow a lot of glitches again!
Personally, my sweet spot is gen 4, but gens 3 and 5 are pretty solid too.