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 5 is my absolute favorite out of them all . I love the plot of this game and also like how it forces you to play with unova’s own pokemons until you have the national dex , which is fun since I won’t be using the same pokemons I always use and will try something new . Also I really have a soft spot for gen 4 , imo it has the best soundtrack of them all .( I personally love the nighttime pokecenter theme and distorted world theme ) Johto was also really good , I like the region’s history . Wished Gen2 had a bigger plot (or a plot at all lol).