I'm partial to thin, velvet matte Lexan overlam.
That, or silkscreened metal, is what you will find on all the old-school dedicated cabinets.
The thicker (1/8") overlays always screamed cheap conversion kit to me.
The advantage to using the thinner overlam is that it has a pebbled finish, so it doesn't show fingerprints and minor scratches the way that the polished finish does.