Personally i’d say XY and gen 6 in general, mega evolutions are excellent and they made an actual effort putting lore into the games (plus i’m french so i may be biased because kalos), ORAS were imo the best remakes ever and are exactly what a remake should aim to be.
Gen 3 has the most memories for me, though Gen 2 will always hold a special place in my heart. My hands down favorite Pokémon game to date though has to be Legends: Arceus. The combat was so refreshing, being able to catch Pokémon in the overworld was novel and fun, the story pulled me in and got me feeling really invested. I haven’t had nearly enough of that game yet.
It was delightful, being thrown into a world where the Pocket Monsters were treated… Like monsters. The consequences of being caught out without any partner Pokémon to battle with weren’t just “run back to the Pokémon center embarrassed”. I mean, they were for the player character, but in-universe they made a point to tell you that people die dealing with wild Pokémon. It was a diversion from the typical formula in a big way, and I loved everything about it. Shame we probably won’t get any more Legends games.