I'm looking at Al for weight savings and no rock crawling, and want to know how strong they are. Did anybody bent one? Broke it? First hand experience, please!
Anybody regrets getting aluminum and wishes they'd gone steel instead? Why?
I recommend the BudBuilt website. He has explanations of the three different types of skids he offers and explains which one is good for what.
I had aluminum for 5 years on a Subaru (used way more than most 4Runners) and I now have 3/16 armor.
What defines rock crawling depends on the vehicle, not the rocks. Saying that you won't crawl means you would not come anywhere close to the vehicle's limits, which means you need no aftermarket skid plates at all.
Aluminum can take hits but it cannot take as many hits as 3/16 steel. Similarly aluminum can be dragged, but it does not "like" to be dragged over rocks. Aluminum skids will bend easily and a lot when challenged. 3/16 steel: repaint and repeat. Finally, you will hit big normally on long days on variable terrain, not when crawling because then you are really focused. And with enough speed, you can bend 3/16 steel, too. So that's another argument for 3/16 steel.
So I would say that stock or used often = steel. Lifted and used not very often = aluminum is ok. Of course, if you live in a high humidity area, then that favors aluminum. If you only do trails rated easy, you don't really need any aftermarket skids even if the vehicle spends a lot of time on them.
Also, different shops offer 3/16 steel skids in different weights. In some cases, the weight savings over aluminum are not as significant (RCI).
