Nothing with modes seems simpler than a rotary switch. It is very easy to turn, even with old hands.
Everyone knows how a volume knob works. Turn it clockwise for more output.
The Sofirn SD05 “diving” light only draws ~70uA when off. It has a 4AH 21700 battery. 4AH/70uA = 2381 days
The self drain on the battery is probably higher than that.
I checked a couple other magnetic ring dive lights marked Volador (Willcrew DX30 and DX60, thought to be manufactured by Sofirn). They also measured 70 to 80uA standby drain.
Point is, magnetic ring lights can be made with low drain. Now they need a USB port for charging. (no longer dive lights…).
The examples given are brighter than necessary. A lower output version of the SD05 with a charging port seems about perfect to me.
Since this doesn’t exist, for gift lights, I like dual switch lights with built in charging. Tail switch is on/off (most people get that), and side switch selects brightness mode. Flashlight works even if you forget it has a side switch! Problem is the charging. The tail switch is mechanical so the light must be turned “on” to charge. Not as easy or intuitive as a rotary switch, but these are available with charging.
FB