Been on a huge Nier kick lately before the Replicant remake comes out and despite my issues with the combat in both games, everything else about them are fantastic and the music is just... Wow.
3rd Strike is still the best SF <3
For some reason Street Fighter has been the only game series that consistently have a great OST. Like the PC-Engine CD version of Street Fighter, which is called Fighting Street for some stupid reason.
I'd throw Guilty Gear in that category as well for consistency in soundtrack