Don, metallurgy textbooks will say that if everything else is the same, same alloy, same final cross section thicknesses, same starting billet block of material, and so on, a forging will be stronger than machining the billet to shape. The forging process deforms the internal grain structure of the metal so the grains "flow" or "wrap" around corners without interruption while cutting metal away puts gaps in the grain structure that can serve as the starting point for cracks. That said, it is almost impossible to get the "everything else the same" part right so you wind up comparing apples and oranges. If proper attention is paid to eliminating stress raisers in the final shape of the machined billet crank (radiusing corners, paying attention to where diameters change, etc), and starting with a high quality billet of metal with no internal inclusions, stresses, or defects, I think a billet crank is probably stronger because my guess is that it is easier to get the shape you want on the throws and counterweights than it is on a forging. Anyway, food for thought.
Check out the link in his signature.
I know Dan Stezo said he would rather use a Eagle rather than a BMS crank. I hoping my Crower Billet crank and Titium rods are the strongest i could get
