What the fuck is going on in this thread? Are people baiting about XY being better or worse than what came after?
Anyways, I voted for XY. I never played Sun and Moon, but USUM were very good games imo. Good amount of difficulty, decent region design with plenty of side-paths and secret areas unlocked through PokeRides even if some of the routes were too linear, great Pokemon variety, and an actually meaty postgame between episode RR, exploring the rest of Poni Island, Battle Tree, and the Wormhole Ride hunts.
Sword and Shield's main campaign was just boring, but I've dumped a ton of time into them between comp, shiny hunting, and raids, and the DLC has some of the best map design in the series, let alone recent gens.
XY I just couldn't get into. I beat the game, caught the legendary birds and Mewtwo, did episode Looker, and never really looked back, I didn't even feel like doing comp despite getting into in in Gen 5, I was just too disinterested in the game to bother. I don't know what it was in particular, but I honestly think the game just lacked personality. Outside of Megas (which really aren't that much of a draw), I feel like it barely tried anything that would encourage you to play it over any previous games. The region's look was decent, I guess, but obviously held back by the 3DS. The region's design was okay, I guess, but it just felt like a watered down version of what came before, especially in the nonsensical psuedo-seasons in lieu of the actual seasons from Unova. The gameplay felt the same as ever, the story was boring and typical, etc. etc. Looking back on it, I didn't hate the game as much I just didn't care about it at all, which is probably the least amount of emotion I've ever gotten from a Pokemon game, good or bad, before or since.