Modular/Prefab horse stalls

Anyone have a favorite company? Asking for a friend. The barn is already built, a 5,000sqft metal building. Wanting to add 6 stalls and person who is looking wants modular or prefabricated stalls.

What companies are good? Bad? Best Variety? Just looking for opinions or examples if you have them. Only specifics I know of are solid walls between horses and possibly a stall front that allows for the head to hang over (but not completely needed as we use stall chains typically).

We went with Priefert and have been very happy with the product!

Trainer here just added to her barn with MDBarnmaster stalls.
That is what her barn was initially and the old ones still look like new.

This is what hers looks like:

http://mdbarnmaster.com/gable-barns/

They have all standard stalls and also custom build whatever someone wants, I think.