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.
I probably need to go back and replay to make a more objective opinion, but I remember the feeling of Gen 2 with the day/night cycle, breeding and baby Pokémon, and then when Pokémon Crystal came out with animated sprites during battle. Definitely my favorite.