Quoted By:
XY have a better story than SM simply by the virtue of not being as prominent and forced.
XY have better level design, not by much, but it's still better. Alola is far too small, streamlined and lacking in aptitude for exploration.
XY have better content. Poké Finder and Festival Plaza are both some of the worst features we've had yet on the account of being immensely grindy, and in the case of the latter, also extremely luck-dependant. I know people love the Poké Pelago because they're either lazy or busy, but it's still literally just waiting, which is a bad thing.
I'm not happy with XY. I'm not trying to say they were good. I felt disappointed and unsatisfied with them. But they're still better than the absolute, nigh-irredeemable Sun and Moon.