I have no experience with them, but Morton does seem to be the standard that others compare to. Kind of like Honda small engines or Kubota tractors.
You also pay more for that, but in the end, having it done well is always worth paying more for in my opinion.
I've built a few pole barns and have tried a few different suppliers in my area. Muellers is the one that I like the best, they have very good metal for barns and buildings with excellent salespeople to talk to when figuring out what you need and explaining what options are available.
I would be very cautious about buying from a national supply chain. You never know where the metal is from until it arrives at your place, and you never know how good they will stand behind what you bought if you have any problems. And every build will have it's own, unique challenges to overcome. How well that is accomplished will decide how much you enjoy or hate the build.
Since you do not know who to hire, or where to go, it might be a good use of your time to drive around and look for newer built barns and shops in your area, and talk to the owner of those buildings to see if they will recommend a builder or supplier. I've done this for concrete, HVAC, Plumbing and roofing contractors, and it's amazing how many I learned about that nobody would recommend!!!!