Which material for a head gasket?

[CMF_Michiel]

I'm planning to order a 2mm head gasket for my K11 turbo, but I don't know which material the best is for the gasket.

I can choose between aluminum, copper or metal.
The turbo going to run on about 8 - 10 psi on a CG13DE.

Which material shall I choose?

Thanks.