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.
I might come across as an obsolete dinosaur (which I probably am) - but I really enjoyed the tracks from Hitman game series, especially Exploration from Hitman 2 : Silent Assasin, and then became a fan of anything composed by Jesper Kyd.
https://www.youtube.com/watch?v=8bGA0y40_38