I mostly use 18650 lights in terms of hours per day, but that's because my most used lights are on my bicycle. I have a rotation of Fenix TK21, Fenix TA21, Klarus XT10 and XT20, Thrunite TN11 and Catapult V1 on my handlebars. Normally twin a floody (Klarus) with a throwy (Fenix TK21 a fave).
But my EDC's tend to be CR123A based. Sunwayman VR10 Ti, Eagletac D25C, Firstlight Tomahawk SE etc.
I think just in form factor and power the CR123A (Or RCR123A) just edges out the opposition.
My favourite lights of all are my ARC's.