Gens 3 and 5. 3 because Ruby was the first Pokemon game I ever played and my favourite Pokemon was introduced in Hoenn (Treecko), and 5 because of the more convenient changes (Such as being able to use Repels without going to your bag if the last one runs out) and the Unova games honestly taught me an important lesson about seeing things not in black and white, but in grey areas too. Also banger soundtrack and art style!
Originally it was gen 2 ever since gen 2 but I came to appreciate the plot and completeness of the gen 5 games to consider that my favorite generation.
That being said, after my recent playthrough of Ultra Moon I think gen 7 could take it. It has some of my favorite new pokemon, the games make for the most heartpounding nuzlockes, it has the best soundtrack (maybe tied with gen 4), you still had the option to turn exp share off, and I just love the experimentation and cultural exploration.
Edit: now that I am thinking about it I think odd number generations have aged better than even numbered ones
While HeartGold has a special place in my heart- pun not intended- due to being my first Pokemon game, Gen V has my favorite story, the most Pokemon I love [literally there's only like. 1 or 2 gen 5 Pokemon I actively hate. Most I love, like, or at least can appreciate], N... ngl I was an N fanatic as a kid. Literally one of my favorite Pokemon cards is N's Zorua from Journey Together! Specifically, the one below.
It's so cute! While I adore Gen V, none of the Pokemon from that game make the top cut for me. My top 5- the most zoomed in I can get- are Chikorita, Meganium, Crobat, Shinx, and Luxray. But I love so many Pokemon that making a top 10 would be near impossible.
It's an unpopular opinion but I really like Gen 6... Legends Z-A finally gave us some clousure to the whole story! It's just such a beautiful region with beautiful pokemon. And it has Sylveon!
