As far as I can tell, and this is an overgeneralization, (see: wrong) there are only three companies that make dampers. Koni, Bilstein, and Tokico. They all make adjustable dampers for those who want to fiddle with the settings. You could get those. But they will be more expensive and you will have to find the right setting. Before you find the right setting, your ride quality will suffer. And adjustables are more likely to fail over the life of the car.
Now, if your getting non adjustable dampers, you'll technically have more choices. In as much as you can buy from FRPP, Steeda, Saleen (??), Roush, etc... But... As you mentioned, all these companies just buy from one of the above mentioned suppliers. I think most buy from Tokico. They rebadge the dampers as their own. This is not entirely bad though, as they essentially work to find the right setting, and then have Tokico make them to that specification. So, Steeda dampers and Roush dampers may both be made by Tokico, but the Steedas may be softer or vice versa.
I bought Steedas, made by Tokico, and they were significantly harder than the stock shocks, made, I think, by Tokico for Ford. I did that because I have the Steeda Springs. I think, your best bet is to stick with the same company. I went with Steeda over Roush because they are priced a bit more reasonably. I am overly happy with my Steeda set up.
But, if you have the Roush springs... probably the Roush dampers are you best bet for a properly tuned damper/spring set up. If you really dont want the Roush dampers, you might want to get some Bilsteins or Konis. People love them.