Here is an article on the nutrient density of organ meats http://www.truthaboutabs.com/weird-nutrient-dense-meat.html

I mean this as a serious, respectful answer but I'm not a scientist so I have to use my own words. My take on offal is that my body has the same bits and pieces and therefore eating bits and pieces from other mammals is pretty much guaranteed to be healthy for me. Whatever nourished the other animal should be in the appropriate tissues so I want to eat as complete a variety of portions as I can.

For example, I eat/drink a ton of bone broth stew because one of my weaknesses is cartilage and connective tissues.

Another non-scientist here. But I'm betting that certain nutrient concentrations ARE sequestered in certain tissues of the animal, so it's apples and oranges between kidney meat and chucksteak, etc. It's just my policy to get as close to nose-to-tail as I can.

That said, my preferences in taste DO affect my purchases greatly. I buy a lot of cheek meat, and procrastinate on tongue. Gotta try a different recipe for tongue, maybe, but I procrastinate.

I'm not sure tripe counts, flavor-wise. It's got no flavor. But that's what makes it good for lending beefy satisfaction to chicken and pork.

I've got kidney meat on order. It'll be my first. Where can I get eyeballs?

My local friendly grass fed farmer just included me some lamb lungs. Texture wise they feel like meat marsmellows. I sliced them and fried. Didnt work so well. Next time i need to show them little meat mallet. Then i tried to grind them into stew stock. Worked better. Sort of paleo gravy thickener. I have no idea what kind of nutrition they have but for zero bux its good. I am sure they are loaded in vitamin c atleast due to alot of antioxidants needed in lungs.