So..... what goes in it?
I don't recall seeing much mention of what to put in all these hi-tech flashlights.
In years past, I did pretty much what the commercials said, unless unavailable all my lights got Duracells (like most every other first responder did).
My childhood memories said that Eveready was OK and every leaky battery I destroyed a flashlight or toy with was a Ray-o-vac but we're talking 4 to 5 decades ago there.
I saw some of the Eveready AA Lithiums a while back, tried them in the GPS and have been using them since for all things AA battery. My newer lights take CR 123s. I honestly haven't used up many 123s to even have a good guess as to what is good/better/best. I bought a package (6, 10, 12??) of Surefires a few years ago at Cabela's (after paying $8 each for whatever brand I could find at a hardware store in the keys, didn't want to get 'caught short' again) and just put the last two of them into a light this week. I haven't used any yet but grabbed a 20 pack of Rayovacs (despite those long ago memories) from BoTac because they were cheap ($22) and what showed up were Streamlights.
My use of lights is so sporadic and spread between several different ones that I can't make a reasonable evaluation as to what is 'good'.
Who knows (or has an opinion) what works?
No one calls the Fire Department because they did something smart!
06 DR 650, Moose RS Holder, Handguards and Skidplate, ProTaper bars, Garmin 60CSx, Motech racks w/ 20mm Ammo cans, Renazco, TKCs summer/17" SM wheels winter 08 Scrambler, Conti Trail Attacks and BlackTiger Fork mod, 05 FSE 450, 03 KLR 250, 02 FXDX, 72 WR 250 (again), 72 SL 350 K2 (again), 72 TR6R, 06 XT 225