I loved X and Y. It made me tear up. Sun and Moon weren't enjoyable for me because Lusamine was... very kooky. Almost bordered on fan service. Also seeing our character's dumb smiling face in every damn cutscene... I didn't finish Ultra Moon but I got to the last Gym. 99% the same aside from new characters butting their way in ever so often, battles with them, and a slight change to the initial Team Aether ending.