Are you talking about the plastic snap together ones? I thing they are over priced and ugly.
Just my opinion
I got a 10x12 metal shed on eBay but it was a task assembling it. It took blitz and I one day to erect it using all their cheesy hardware but the end result was pretty sturdy. Then I added a extra layer of plywood on the floor and built some heavy duty free standing shelves. It's in my garage build thread if you want pics
I dropped a big tree limb on it without damage and it withstood 60 mph winds so far
I checked on prices of wood sheds and quickly learned they really want all your money weather it be a assemble it yourself or buy one built Then charge you again to deliver.