Where do I begin?
Well recently I really liked the score for The Last of Us, particularly the gentle acoustic guitar piece used frequently in the game, everything about it just complimented the game. Ditto for the music in the Crash Bandicoot games, they were perfect for the world of Crash and they were super catchy, I still remember them today. Also Red Dead Redemption's score, perfect western music and (while I know it's cheating) the inspired use of Far Away by Jose Gonzalez in the Mexico moment. Then there's both the Borderlands games, I know the actual OST may not be to some people's taste but I just love the drawly, slide guitar-y background music you get, especially in Fyrestone in the first game.
Then there's the varied soundtrack of Final Fantasy XII; I think the game as a whole is underrated but the sheer amount of music for the many varied areas of the environment alone is amazing enough but each piece of music is also so well designed for each specific area and so great to listen to, I think my personal favourite has to be the jaunty baroque-y music you got in the various safe areas (home cities etc). Also Point Blank (mostly 1 + 2) almost entirely for the menu music which managed to be quite basic and appropriate for an arcade game without being repetitive or irritating. And how can you talk about great music in video games without mentioning Parappa the Rapper?! Or for that matter a gem a lot of people missed out on - Gitaroo Man; it takes real skill to write music that's still great listening after two dozen times hearing it in a row trying to beat that one difficult level. on Also Portal + Portal 2 basically for the end credit songs Johnathan Coulton wrote for each game.
Plus the Hitman games (not including Absolution, just the games Jesper Kyd did the soundtrack for) as a whole had fantastic music, also Assassin's Creed 1 + 2, (really just anything Jesper Kyd's done, he's probably my favourite video game composer of all time) Uncharted 2 (and 3 to a lesser extent), and XCOM. And finally the beast that is Skyrim. I did all my revision in the third year of my degree to the Skyrim soundtrack plus it makes great music for playing the Game of Thrones Board game or D & D and of course it fits perfectly for Skyrim itself - it's epic, huge, and varied while still keeping to a core style.
Even money says I accidentally ninja someone with at least one of the games in this list.