I'm a gravel lover and would go with black, "glittery" (not dull), fine gravel like Tahitian Moon sand.
The fish will feel more comfortable on the dark underground and the colors of the fishes and plants will come out better
It is still soft enough for catfish and easy to clean, plus you will have less algae growing on there, since it's darker.
Previously: 2x 10gal tank, 45gal aquascaped, 70gal aquascaped
Currently: 16gal FW, 40W CF, ADA Aquasoil Amazonia II/Tahitan Moon Sand, PH 6.5, kH2, gH 4