Are you looking for a specific brand name? Many of us here base our pellet usage on the results we get with our own rabbits. Some use differing protein levels based on the rabbits show or reproductive status, its stage of growth, etc. Others use pellets as a supplement to a feeding program that includes other food sources. You have to find what works best for YOUR rabbits without going into serious negative cash flow-- yes, certain feeds can be very expensive.
Me, I Like the Buckeye brand pellets. It is a locally (in state) produced pellet that makes adjustments in their other livestock feeds based on where the bag is being shipped to. I also feed other sources, such as fresh forage, REAL hay, BOSS, A specialty horse feed, etc.. I change my rabbits diets for weather conditions, pregnancy and breeding, And weight maintenance.
hope this helps-- there are as many answers as there are members here!!