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?
Pokémon Generation 1 and 2. They story, gameplay, and mechanics are concise and not hand-hold-y, the designs are the ones I grew up with, they can easily be played on a phone emulator and have so many rom hacks that I never will totally experience everything they have to offer