I think Pokémon peaked at Alpha Sapphire/Omega Ruby, but to be fair, I was the prime target audience. I prefer this generation because it was 3D while still having the 2D gameplay feel. The mega evolution was still novel and consistent with the previous games. The new 3D games are so convoluted with the different Pokémon forms and moves. My preference is late 2D games (Black 2) and early 3D games (Alpha Sapphire).
The 3D for sure. I love the original Pokemon games, but I think the best part of Pokemon is how awesome and wonderful the world is, and the feeling of exploring it, and that's better in 3D. Despite their faults, I thought Scarlet and Violet were fantastic
I prefer the sprites as well. The pixel art had so much character and were well done (except for the rotation and scaling in gen 5). The modern models feel honestly kind of flat and simplistic. Hell, despite these creatures being like animals, there are no effects for scales or fur on their body.