18650 or 2 RCR123A Batteries?

So i have a 2w 445nm M140 Module with an X-Drive preinstalled and a C6 Copper host, and i know i can run the laser off either a single 18650 or 2 RCR123A batteries.

I know using 2 RCR123A batts will output more volts than the single 18650, and i definitely want to use my laser to its fullest potential...

That being said..

I dont want to overpower it by any means.

Will a single 18650 at 4V be better than using 2 RCR123A at 3.7V each? I want my laser to be bright but i dont wanna burn it up.

Its my first laser build.