D4
D4S
E07 (21700)
S43
etc…

don’t have to run a light on max. E07 would be my personal best if Fireflies wasn’t known for massive qc issues and poor support. I use my D4 below the first ramp flicker (>400ma, high efficiency) and it lasts longer than all my other lights while still providing more lumens

edit: but these aren’t usb rechargable, I think it’s expecting too much for usb charging and limits your options considerably.