Lofi beats are nice and all, but honestly I’m able to focus best with black metal. It’s oddly relaxing. Just a solid wall of noise, with no chance of understanding the words. It’s what I listened to all through grad school, and back when I had to work in an office.
Such as:
Leviathan - X (demo)
Krallice - esp first four albums
Yellow Eyes - anything
Ustalost
Judas Iscariot - Thy Dying Light