Adamantium. Essentially indestructible. Created by Dr. Myron MacLain back in World War II. Its invention turned the tide of the war…in Marvel Comics.
For a realistic alternative, you could go for tungsten or titanium…if you have that kind of budget.
Point being, the material is there to hold your sign up for generations.
It becomes a Cost-Benefit Analysis between:
Once again, if the design is the same, metal will be stronger. That's simple. Steel is always great. Aluminum is quite durable.
It's more cost-effective and can be durable.
They can be backlit or front-lit by spotlights, canned lights, whatever the design comes up with.
PVC plastic, ALUCOBOND® aluminum composites, and ALPOLIC® metal composites are three go-to examples of providing low-cost, durable alternatives to give the look and feel of metal & acrylic.
Back-lit signs will require one design style. LED message boards require a whole different framework to keep stable but might need lees to style it.
Design vs. Durability. Form vs. Functionality. Questions as old as time.