Full discretion, I played S/M before I played X/Y and I completely disagree.
While I will warrant that X/Y had the better QoL, that's about all it had. The region felt bland, the story was practically non-existent and Team Flare was boring with Lysandre practically being Cyrus 2.0. Not to mention they had probably the worst champion in Diantha who shows up like twice the entire game and has a team that can be steamrolled pretty easily (I think I was 10 levels below her when I beat her.) The gyms were also very forgettable as well if you ask me. It wasn't all bad though. Mega evolutions are neat, although the Gen 1 pandering and the over-poweredness of them ruined them for me, Pokemon designs were cool and AZ had potential, but unfortunately nothing was done with him.
S/M are by no means perfect, but I think they are the better game. The world, while linear, doesn't feel nearly as bland. The characters have more personality and reason for existing beyond helping the MC. They tried to shake up the formula, and while I'd say I still prefer gyms, it was still pretty cool to see what a world looks like without a Pokemon league. Alolan forms are a neat idea that could be used in the future (but probably won't be.) They introduced more new Pokemon - including the Alolan forms. Z-moves are a cool nuke button that every Pokemon can use, not just fan favorites.
I guess for me it's not that S/M got more right than X/Y, it is that X/Y got more wrong and played it too safe.