I have to admit.
Let's say they were all the same price.
And we had:
Aluminium, Polished Steel and Gold plated (I say gold plated to keep it cheap)
So they were all the exact same price, and it was only looks you were going with.
I'd go for the Aluminium model as it's looks, to me, fresh, clean and modern.
The shiny steel looks cheap like old chrome on a car and chrome/shiny is so 1960's, 70's and 80's We are way past that.
Gold just looks tacky and tasteless, unless it's a small highlight.
Aluminium would be my preferred look
It's a personal thing I know.