I’d say the biggies are Steelcase, Herman Miller, Knoll and Haworth.
But honestly that style of desk is really old-fashioned. Where I work, we buy desks like this, with rolling drawer units for storage. Many of these desks have electric motors so they can be raised or lowered.
This is built to order so it takes some time, but the Amish make amazing furniture.
I bought an oak desk from them a few years ago that I love. Todd is the owner. I pre-paid by check instead of using credit card and I think he gave me about a 2% discount.