If they’re internal drives then you choose.
I like to mount drives at root, their parent directory being the logical purpose of the drive.
Got a drive you added that’s gonna be for games?
/games
Is it for movies?
/movies
Or maybe it’s just general data storage?
/data
No need to make it more complicated than it has to be.
This is standard across the industry, unless you are mounting disks that would conform to another strategy (say it’s a drive of repos, it might mounted under /usr/local/src/ as that’s where one would expect user provided source code).