For me it’s definitely gen 4 (heartgold and platinum are just. top tier), but gen 5 is really close. Really polished and challenging games all around
I also think gen 7 is pretty underrated, especially USUM which got a bit of hate for being too similar to Sun and Moon. Which is kinda true…but I think the end result was pretty good all things considered.
Gen IV, solely because of HGSS. Gen II holds a special place in my heart. Gen I is were I started, but I found Gen II to be everything I ever wanted in a game. Until HGSS changed that by making it almost perfect.
Honorable mentions: I’ve really like gen XI because of all the quality of life changes, the story was surprisingly emotional (not great, but better than any other gens as far as I’m concerned), and the terastilization is cool as hell. It genuinly changes up how I plan my teams and I get to experiment with Pokemon I don’t usually like or that have types that ruin them. Gen VI was dope too. Megas were awesome and ORAS is the definitive way to experience gen III.
Edit: Also, Gen VIII because legends Arceus was refreshing as heck. Genuinly made meaningful changes for the better and felt good to play. Despite being a much more limited experience. It was focused and fun. Probably my second favorite Pokemon game. SHSW were pretty weak, all things considered, but Legends Arceus was special.
