How do you shop for general stock, broth and bone broth?

How does everyone shop for stock, broth and bone broth?

For some reason I have it stuck in my head to look for ones with higher protein content but I am not sure if that means anything. What else can you look out for?

When shopping for a recipe that calls for specifically broth or stock how much do you feel the need to specifically match it or just use whatever is more available. Will you use a broth in a recipe that calls for stock or vise versa?

Bonus question: How do you personally quickly improve a store bought stock or broth?

I will sprinkle in some gelatin in a bowl of the liquid to hopefully improve texture of sauces.