I have had many sheds of varying designs and makers, all built to house specs with 16oc 2x4 studs, etc.
I had a slab poured for one that had a standard garage type overhead door.
For me the Tuff Shed has the best floor design/system, a steel framed door, and the vertical siding is way better than T111.
TS shop builds the walls and stick builds the floor on sight, erects the walls, then stick build the roof (with trusses).
I put in transom windows (up high) to let it light but too high to look into.
I have bought narrow windows (14") and 12"x12" (for transoms) off amazon that fit between the 16oc studs, no framing required, sold as Play House/shed/chicken coup windows, ebay might have them too... way cheaper than what TS sells.
https://www.amazon.com/s/ref=nb_sb_ss_c_1_12?url=search-alias=aps&field-keywords=shed+windows&sprefix=Shed+windows,aps,224&crid=3EDSLIM8MHZJI&rh=i:aps,k:shed+windows
A 200 square foot limit is a common residential restriction for sheds so my go to size is 12x16 with 8' walls and steeper pitch ranch type roof to allow me to build a loft on each end for storage.
The barn type sheds sold by Tuff Shed are the best bang for your buck, as you can build a loft/2nd floor you can stand up in
.
I live near "wilderness" and the Tuff Shed builders/installers told me half their business is "dry cabins" built out there.
People buy Tuff Sheds from Home Depot because they can use their HD credit card but the models sold are the lower grade/end sheds that TS makes/sells.
hope this info helps you decide on a design or builder,
Pics on request...