[DaBackpack]

this question is ultimately meaningless because it's ill-defined and everybody has their own opinions as what constitutes "best video game music"

Is it the game with the best individual songs? Are these songs judged in a vacuum, or are they judged in the context of the games they came with?

Is it the most consistent soundtrack?

Is it "best of all time", or "best of THEIR time?"

If it's "best OST all time, with the best songs and the best atmosphere", I will stand by Umineko. Literally nothing compares, not even Chrono Cross. It's a 200-song monolith of 10 different genres and 15 different composers for a fucking indie visual novel. It has full playlist material of stand-alone music as well as atmospheric, ambient music.

But realistically, I think the question is most meaningful when we're talking about "best soundtracks of their time." The most historically significant OSTs are Super Mario Bros., Megaman 2, Castlevania 2, and Final Fantasy. These soundtracks more or less paved the way for video game music ever since.

Specifically, I would say Koji Kondo, Nobuo Uematsu, and Yuzo_Koshiro were the most prominent composers of that time.