Windows is the best desktop OS for accessibility across the board. Consistent UX, broad app support, better tooling. Not true for every use case, but incredibly broad adoption by disabled users for good reason.

(Also the best compromise between usable business desktop, & IT controls. Linux is not a reasonable desktop environment for most workplaces, and macs inexplicably lack enterprise tooling.)

In other words, like every OS, excellent for some use cases, terrible for others.