hmmm, some notes from my experience in hundreds of button cell lights and a few dozen AAA/AA lights. Most of the recipients are not flashaholics and have no interest. They use their lights, not play with them....
The lowest-cost button cell lights available from just about everyone for <$1: I purchased only those that click on and then click off. No press & hold with a switch to keep it on - unacceptable and later the switch is unreliable. I have had a lot of problems with old cells, sometimes dead upon receipt, mostly about 1/2 dead. yuck. I purchased 100s of these. I no longer purchase these.
The Photon Freedom compared with the Photon X-Light: The Photon Freedom is much more difficult to depress the switch with a very weak tactile feel. The X-Light is relatively easy to find the switch and to depress it with a very perceptible tactile feel to the click. In cold weather that makes a major difference. I have not had problems with either light in my pockets,. I like the covert nose for the Freedom and the many colors! For 2x2016 cell replacement, the X-Light is super easy to open and close. The Photon Freedom is difficult to open and questionable to close. I ruined at least one cover by mashing it when it did not fit. I purchased a couple hundred of the X-Lights with no complaints from nurses, RAs, and one doctor, etc. They like the ramping (which is common to the Freedom as well) and easy click for on or off. I purchase 2016 cells a hundred at a time to drop the cell price and provide at least 4x 2016 cells with the light.
The eGear Pico using 4x LR41 cells is bright, ~10 lumens, but the cells are kinda low capacity. Easy to use though with a twist on and twist off. I purchase the LR41 cells on the internet for < $0.30 each so the price of use is not high. The key advantage is size. My older granddaughter runs around a lot with hers....
The Streamlight Nano also uses 4x LR41 cells, also ~10 lumens. However the twisty head portion is far too long to easily twist. nope. The Pico light is more usable.
I have not been tempted by the Fenix E01 because of only 10 lumens in an AAA format and the beam color.
The Fenix E05 is OK, but suffers from a bit of production variability in beam color and brightness.
The Fenix LD01 is good. and accepts the 10440 as well. just do not leave it on high too long!
The Fenix LD15 is great for a single AA light. Only 2 levels and the intial turn-on is on high! I found out later that the initial turn-on of high is important to most recipients.
In any case, if an AAA or AA light does not tailstand, I will not purchase it.