Whey protein is usually considered the best form of supplemental protein. The problem is that many whey formulations contain ingredients that some individuals are allergic to. Our lab found similar gains in muscle size in subjects taking beef and whey protein powders over an 8-week training program. Therefore, beef protein powders are a good replacement protein supplement for individuals with dairy allergies.
Reference: Sharp, M., et. al. (2015). The effects of beef protein isolate and whey protein isolate supplementation on lean mass and strength in resistance trained individuals-a double blind, placebo controlled study. Journal of the International Society of Sports Nutrition, 12(S1), P11.