Efficiency isn't what you need. High thrust and reusability are much more important. For applications like BFR and Starship you need high thrust to surface ar

Efficiency isn't what you need. High thrust and reusability are much more important. For applications like BFR and Starship you need high thrust to surface area -- a rating you never see. Otherwise you need high thrust to weight. Efficiency does matter, but the other things are first. Finally, a more efficient burn cycle will help more if you can also make the fuel pumps more efficient. (Classic engines have pre-burners. A detonation ring engine might need a plain burner turbopump.