Once you are lean enough , if your vascularity is still lacking you can try Adenosine Monophosphate (Synthelator) , it will definitely increase the effect.
Some people are just not as vascular as others , even when I'm not really lean I'm still pretty vascular.
A major problem some people have with losing vascularity once they are lean is depleted and dehydration , they simply don't have the blood volume and pressure for the veins to "pop"
But to answer your question I think that The IGF-1 would give a faster effect especially when some people hold water from HGH