Porosity is what you are looking for in base rock in my opinion. A larger surface area for bacteria and sessile organisms to cover. I've used tufa, regular old texas limestone and 'reef bones' which is coral rock sold by Caribsea I think? The texas limestone got some cover but never looked nearly as good as the tufa and the reefbones are indistinguishable now after a year from well established 3 year old live rock.

Be careful with some things such as lava rock, lattice rock etc - they can have high amounts of ferro-silicic compounds and these can leach into the water column fueling algae blooms.