Liver definitely has more nutritional density than bone broth. Liver is chock full of vitamins, minerals and nutrients while bone broth is mostly water with a low concentration of minerals.
One isn't necessarily better than the other though, bone broth is better if you're dehydrated and liver would be better if you were otherwise lacking minerals/vitamins in your diet. Too much liver could be bad too, specifically because of the vitamin A.
If pressed: liver is "better"
But really it depends on the rest of your diet. If you're already getting what liver offers, bone broth could have a greater impact on your health and quality of life.
nutrient density is the amount of nutrients you get per kg. Water would have a nutrient density of 0. You could argue that a product's water content is an inverse measure of nutrient density. Bone broth is extremely UN- "nutrient dense". So therefor it is liver.
Although I would eliminate liver from my diet before bone broth.
Essentially I think you'll get the most profit from consuming liver, else you'll be losing all the extraordinary fat solvent vitamins unless obviously you utilize the fat from your stock, admittingly I dispose of the majority of it.