The alpha wolf in a pack, as well as the male lion in a pride, prefers and eats the liver first, the heart second, and takes the bones with the most marrow in them third. Meat goes to beta wolves and females.
I just ate some grass fed beef liver and it was delicious. I'd been putting it off because I couldn't figure out how to cook liver before and fucked it up several times. The trick is to find which way the ventricles in it go first, then slice it crosswise and thin, then lightly saute it for just a few minutes (2-3 minutes, not more than 4), just enough to get it something like medium rare.
The cheweyness that people don't like is the ventricles, so you cut it across the ventricles, sort of like how you have to cut brisket a certain way or you make a chewey mess of it.
I will be trying kidney sometime soon, next time my butcher breaks down a calf, will report back with results. Might also try this biltong stuff with a heart in the meantime just to see how it compares to jerky.
Those of you in places where meat is expensive, check the prices of offal, fresh grass fed beef liver is $5CAD a pound here, which is slightly cheaper than a 1lb pack of shitty supermarket 80/20 regular ground beef where I am. Shank bones are like $3-$4 a pound.