The best BCAA (branched-chain amino acid) ratio can depend on individual factors such as diet, workout routine, and goals. However, a ratio of 2:1:1 (leucine:isoleucine:valine) is generally considered to be the most effective for promoting muscle protein synthesis and recovery after exercise.
Leucine is considered the most important of the three BCAAs for muscle protein synthesis and growth, and isoleucine and valine play supporting roles in the process. A higher ratio of leucine to the other two BCAAs is sometimes recommended, but the 2:1:1 ratio has been shown to be effective in several studies.
It's important to note that while BCAAs can be beneficial for muscle recovery and growth, they should not be relied upon as a sole strategy for muscle growth, and a healthy diet and exercise routine are also important components.