Lard, tallow, mink oil all work for me. I do not know if there is one best. Try several and see for your self. Although the amount of test might be overwhelming.
Let us say you try 70 grains 3f behind a .495 ball with .15 patch. Then you try moose milk, mink oil, spit, and you settle on moose milk as the best. But.... What if you dropped to 65 grains, or increased to 80 would moose milk still be the best? Oh my.
Your best cambo for one charge may not be the best for another. Then, seventy degrees might not be the best at thirty degrees. And so on and so on. Not to mention Swiss works better with moose milk, g o works better with mink oil and crisco works best with pyrodex, and so on.