Optimal macro ratios for muscle gain?

First off for optimal muscle gain you want to be eating in a surplus. Calories will be king.

Macros are important too but I would not go by % because someone gaining on 2500 vs 4000 calories the ratios will look a lot different. Better to use grams per lean body mass:

Protein: 0.8 to 1g
Fats: 0.4g
Carbs: The rest

Keep in mind these are minimums and you can adjust to your preferences and needs