Steel vs Aluminium strut braces. Which is the better option?

[ByronRichesMk1]

Okay, so i'm looking at purchasing a upper strut bar for my Mk1 (one piece), and I have an option of either an aluminium one, or a steel one.
I do realise the aluminium one would be significantly lighter, but would it be stronger? Or would there be a fairly negligible difference in strength? Especially since there is something like 40pounds difference in price for the two..

Cheers!