Another vote for Snowbelle City's theme. It's nice and relaxing. Since Kalos is such a busy and showy metropolitan region I like Snowbelle becauase it's different, a contrast. This place is quiet, quaint and pastoral, and shows a more intimate side of Kalos. The music is a vital part of why the atmosphere seems calming to me, along with seeing the fluffy snow sprinkle down. I think the theme music does a good job capturing how alluring winter can be. The gentle xylophone notes sound like falling icicle droplets.
XY doesn't have my favorite soundtrack, even though I do like the games, I think that the battle themes can get a little distracting. That being said, it has some interesting tracks, especially for the location music. I'm glad that Sydian mentioned Anistar City's theme, because I had forgotten it, but hearing it again took my breath away. The rhythm of the bells and gong weaves this exotic, fanciful ambiance that fits the strange but beautiful dreamscape of the city with it's psychic Pokemon and big Crystal sundial, and that whistling sound you here is unexpected and whimsical.
Shalour City is also something. Even though Kalos is inspired by France, the music of this environment feels more suggestive of traditional Japanese string instruments. The space feels majestic and earthy and fit for a proud warrior, a great choice for city that has the fighting gym and also holds the ancient secrets of mega evolution.
