Recommendations for outdoor storage shed

The 6x8-ish shed that was here when I bought the house is I believe a "Robin" brand.

Wood framed with a thin metal skin, and a wood floor on risers with hurricane augers.
Wide, hinged "mobile home style" metal clad door.

It's definitely more solid, but it's 10-12 inches above grade and only has a 38-ish" wide door, so no way to get the mower into it. I have to use cinder blocks to make a step to get in to it.

Stuff also gets dirtier in the metal shed on the slab than it does in the Robin shed.

That might be a function of the mower in and out and grass clippings and dirt, or it could be that the Robin shed is sealed better.

I have interior and electrical parts in the robin shed and axles, suspension, and brake parts in the Lowes metal shed.

However, some animal burrowed under the Robin shed and it's now listing to the rear about 5 degrees.
Gonna be a beotch to make that right.