No, not a topic about sales. Which generation of Pokémon games do you prefer and why? 

They both have a metacritic score of 87%.

I don't know. I just finished Moon, and I've yet to try the postgame content. For now, X/Y is above Sun/Moon, but only because it tells its story better, in my opinion, and does not feel cramped by the 3DS's capabilities. I hope Pokemon Stars on the Switch makes Sun/Moon justice and creates a postgame akin to HG-SS/Emerald. Exploring Kanto again and the Battle Frontier. Now THOSE are postgames.

Sun>XY, although they're both great games. Can't see why anyone would trash on one and praise the other. Both generally fall short in the same areas and improve in the same areas.

I'm just glad Sun/Moon had a deeper story(although it wasn't the best)

Lol Sun and Moon easily.
X and Y was alright if the online competitive scene was your thing but Sun and Moon does that just as well along with an amazing single player and post game.

I liked both, but I personally preffer XY, to put it simple: the things about XY that I dont like dont spoil the game for me, whereas the things about Sun/Moon that I dont like reallly, really have a presence.

Black and White

What? Killing everyone that isn't part of his little group because they're not beautiful is a terrible story that makes no sense. That was easily one of the worst parts of X and Y for me.

Definitely SuMo. X/Y just felt so shallow. If it wasn't for the newly implemented 3D visuals in X/Y then it would probably be my least favorite main Pokemon game.

Sun and Moon. It took everything X/Y had and made it 1000x better. And the story actually had thought put into it for once. X/Ys story was laughably bad. The region was nice but it had a lot of wasted potential.

However, despite me preferring S/M more, X/Y do 3 things better; online, not nearly as much lag, and WAYYY better clothing variety. To me it seems like S/M wasn't initially going to have clothing at all, but was tacked on once they realized they can't go back to standard trainer designs anymore (ala ORAS)

Sun/Moon's story is better than X/Y, but only marginally so (the only big flaw Y/Y's story has compared to S/M's is the weakest team in existence), but I feel X/Y told it better. Sun/Moon starts with a very interesting intro, then nothing really happens until Lillie gets kidnapped. After that, the story unfolds way faster than X/Y, which I think is an error in pacing. At the very least we know that a story is unfolding in X/Y from begginning to end, with way better progression. Plus, the ultrabeasts are too vague a threat compared to Team Flare's killer laser.