The Command and Conquer series can't get enough love, and as mentioned before, Red Alert 3 has that great over the top music, but I have a soft spot for Command and Conquer 4: Tiberian Twilight. Sure, It's way too different from the original gameplay and is rather rough on the edges, but that soundtrack is unforgettable. My favorite is this one, Welcome Back, Commander:
Endless Legend has nice ambient tunes, nothing too dramatic like something you would find in a fantasy game, a gentle soundtrack if you will:
Far Cry 4 soundtrack revolves around contemplative and exotic music and suddenly changes to some tracks with fast tempo and modern beats, not unlike the game itself. This is a great soothing one, The Mountain Watches:
Dragon Age Inquisition is a triple A game and likewise has a Hollywood level soundtrack, my personal favorite:https://www.youtube.com/watch?v=AA0pbPfLm60
Broken Age from Double Fine Studios managed to create a quirky and interesting soundtrack:
Planetary Annihilation has possibly one of the most epic game soundtracks of all time, but that's a requirement when you are throwing entire planets at your enemies! As a side note, there are similarities between this soundtrack and Gustav Holst's symphony The Planets, so kudos for a great reference!
Composed by Steve Burke, Kameo: Elements of Power has this powerful and fantastic music, way above your average soundtrack:
Killzone 3 also is a heavy weight with it's full symphonic soundtrack, not far behind John Williams:
Wolfenstein The New Order is a strange but beautiful one. There's this weird 60's vibe in the background, almost psychedelic, and then from nowhere it dives into a full throttle horror, as if someone started drilling your skull with an industrial grade power tool. Lobothomy has never been so sweet: