I know you probably love a dozen tracks, please pick one, thank you in advance.
EDIT: Thank you all so far, especially everyone who kept it to one. I am at work currently and will make my way through the list but may not get a chance to thank you individually. I am checking them all out though and appreciating it.
The whole soundtrack is good, but:
Counterattack from Xenoblade Chronicles 2
I especially love the way it subverts the rhythm and modulates the key going into the final refrain around 3:45.