The color of the base is certainly a consideration. My thoughts and experience are that to gain contrast within the highlight regions two primary factors play a part. The first being the negative from which we are printing. That involves the films characteristic curve and where the highlights fall on that curve. If the highlight densities fall on the films shoulder they will not be separated as well as if they were to fall more on the straight line portion of the curve.
Originally Posted by Scott Edwards
Coupled with this on the film are the choice of developer. Developer choice and dilution can alter the slope of the curve. A pyro developer will afford staining (additional density) that is proportional to the silver density. This proportional stain thus affects the highlight density region to a much greater extent then the shadow region. Certain pyro developers stain with different color. PMK will normally stain a yellow-greenish stain, ABC will be more black in color but it can go green if the B (sodium sulfite) solution gets several weeks age to it. Pyrocat will give a tan to brown stain. The reason that the color of stain is important is that with VC materials the green componant of stain will work as soft contrast filtration in the highlight regions. Thus the place that we want separation of tonal values is compromised by the effects of softer filtration from the stain color. In my experience Pyrocat does not suffer from this malady.
The other factor that then is involved is the characteristic curve of the paper and where the negative highlight densities fall on that curve. If they are placed on the toe they will not separate as well as if they are placed higher on the curve.
My point is that there are several considerations apart from the paper that may be involved in your search for what you want. I have no axe to grind in this regard because what you and I want in a print may be different. Good luck in your efforts.