Here's My Top 10 List of the Songs in Pokemon X/Y:
(1 being my favorite and 10 being my least favorite)

10. Wild Pokemon Encounter
9. Cyllage city
8. Team Flare Lysandre
7. Team Flare
6. Pokemon Amie Tile Puzzle Mini-Game
5. Elite Four Battle
4. Pokemon League Theme
3. Rival Battle
2. Champion Battle (Vs. Diantha)
1. Legendary Pokemon Battle (Vs. Xerneas, Yveltal, or Zygarde)

What's your list?