[Xringer]

I would look at the weights first. The steels are not as thick as aluminum.
I once purchased a Honda aluminum body lawn mower.
The body needed to be rock proof, so it was a lot thicker.
Turned out that the same lawn mower in steel weighted about 18 pounds less..

One other thing to think about is the installation of disc hubcaps. If you get the the screw-on type, you will have to drill holes in your rims edge (where it's thin) and tap the holes for screws.
To keep from stripping the screw hole out, steel is stronger, and would be the better metal for this application.

Aluminum is a soft metal. If you hit something in the roadway and it compresses the rubber down to the metal, steel has some flex to it. Aluminum castings have very low flexing before they crack and break.
Accidents happen. I would rather run over a spilled load of bricks with steel rims, since they aren't likely to break into pieces and fly apart.