Soundtrack is more important to me in a video game than anything else. A good soundtrack can make me overlook gameplay or a story that is absolutely terrible, and bad soundtrack will completely ruin a game for me regardless of how much I might enjoy it otherwise. I NEED a good OST to immerse myself in a video game: it sets the mood, draws me into the world and the story, and more than anything else provides an immersive experience. You cannot have a good video game without good soundtrack. It is essential.
Good VGM...I could go on and on here. NieR (the original, although Automata is a close second) stands without peer, but Xenoblade Chronicles (JUST the original; 2 has by and large a mediocre OST and Sawano is very hit-and-miss with X's score), the Castlevania, Monster Hunter, and Etrian Odyssey franchises, and Bayonetta 2, all stand out to me right now as examples of good video game soundtrack.