Even if the surface resistance is worse than most metals, for example, carbon fibre, RF reflection seems to be nearly total.
The wavelength matters also. It is possible to use chicken-wire, or wire mesh without any loss of gain if the gaps in the wire are less than 1/10 of a wavelength.
Think also of frequency selective surfaces used for sub-reflectors with dish antennas. An array of little crosses, resonant at X-Band, on a material transparent to S-band signals, gives less than 0.1dB loss through the surface, and less than 0.1dB loss on the X-Band reflection.
I doubt there would be any significant difference between various metals used as reflective surfaces.