Batman Arkham City, I love the way it is reminiscent of Hans Zimmer's music from the Christopher Nolan batman movies, but still sounding original.
Skyrim, for all the reasons everybody else said.
And the Mass Effect trilogy. Mass Effect 2 in particular. The music from the Suicide Mission at the end of Mass Effect 2 especially. It has an epic, fast passed, frantic energy that perfectly matches the tone of the mission. It’s probably my favourite video game music ever. It also sounds very similar to the 11th Doctors theme from Doctor Who.