“So just for around the house work and short walks which type of lithium Ion powered flashlights are most favored? I vote for 14500 size cells.”
My favorite is 16340/CR123A. The reason I say that is that with a few 14500/AA lights that I’ve tested, I’ve found the 16340 to perform as good if not better from an efficiency standpoint even despite the fact that the 14500 will have 100mAh more capacity. And the only explanation I can offer is that it has to be related to the type of electronic driver to cover the voltage range from 0.9v up to 4.20v……….which overlaps the typical Vfwd of an LED around 3.0 volts. This complicates the driver. Some cheap out and use PWM when using a 14500.
The Nitecore MT10A and Jetbeam Jet I MK use a good efficient boost driver for the AA battery and PWM for 14500. The Jetbeam Jet I MK is one of my favorite AA lights but I keep an Eneloop in it.
4-Sevens was probably one of the first to put 0.9 to 4.20v driver capability. I found their lights were not as efficient as others that did not cover that voltage range.
The Fenix E15 and PD25 with a 700mAh 16340 have better run times per comparable output than do the LD11 and LD12 using an 800mAh 14500.
So after discovering this I absolutely fell in love with the 16340/CR123A size and only considered AA/14500 lights if I was intending to use them with an AA Eneloop. Disclaimer: I still use a 14500 in the two LD11’s that I have……….knowing that in a pinch I can always use AA. And that I think is the most important aspect of an AA/14500……….the fact that it will take a very common battery.