Morgan makes a decent building for what it is, I used to be in the back yard building business and they were the biggest competitor. Many of their dealers are factory owned, leads to less personal interaction but sometimes a deal can be had.
I don't like the fact that many of their designs don't use floorplates on the walls, the studs are nailed directly to the floor but that's me. Also, I found out that the problem with painted wood is that it always needs repainting. We used 28 gage corrugated steel with baked on finish but that's an esthetic thing that you have to decide on.
Get the biggest building you can afford, you will always find stuff to go in it and price is better for larger buildings than for smaller, on a square foot level.
Definitely get the 3/4" floor option, they typically (used to) use 1/2" chip board over 24" OC joists. Get 16" OC joists also, usually not an expensive option and will pay off later.
Doors can be cheaply hung, windows used are mobile home style and usually are expensive. If you're handy with your hands, make sure they lay out the walls to support you putting in your own windows and then pick them up from a mobile home supply place. Don't try to use standard house construction windows, they won't fit and will leak. You need a window that fits flush with the wall and has a lip around the outside edge to screw in place.
Talk them into delivering and setting it up as part of the price AND get them to anchor it with mobile home anchors and straps. Shouldn't cost more than $100 to anchor it with drill in anchors and if you live in tornado alley you will be glad you did.
Dan R