His preferences are pretty specific and so far I haven’t come up with the right light.
- No backlit buttons (except as charging indicators)
- No tail switch
- No built-in charging (this really narrows it down a lot)
- No large reflector head
- 1 x 21700 form factor
And he didn’t say it, but he also expects
- a semi-focused beam
- intuitive UI
I thought Convoy was perfect until he vetoed all tail switches. 
Any ideas?
Fenix E35 V3.0 if he don’t care about green tint and low cri.
I guess the aux and switch lights can be disabled. Maybe I can even get Hank to substitute a black button. But I’m not so sure about that knurling. It would also nice to know how long it can sustain various brightness levels. I think my brother would want flat output levels on non-turbo settings since he wants a more serious light.
Define ‘more serious’
Performance oriented. No flashy aux lights or backlit switches, no different knurling for the sake of being different. He wants a light that is completely dark when turned off and he is more interested in ease-of-use than having extra features.
I was liking the looks of this one but having to hold 1/2 second to turn it on would probably drive him crazy. He doesn’t care about CRI though. For tint he prefers cooler ( :confounded: )
Convoy M3-C, M21D (you can get it in 5000K) or Thrunite TC20 V2 (they also make a MW version). Simple UI rules out Anduril/Anduril2 and NarsilM.
I actually thought of the M3-C and TC20 V2 but they are both a little chunkier than I was aiming for. I showed him a 21700 light and he liked the thickness of that. But the M3-C and TC20 sure tick a lot of performance boxes so I might have to consider that if he gets the light he is asking for he might be disappointed by the performance. If they didn’t both have built-in charging the decision would be a lot easier. He is worried about water ingress.
The Wuben C2 is a nice light I’m testing now. 21700, easy UI, built in charging. Smaller than the Convoys.
Zebralight SC700d checks some boxes but the xhp 70.2 may be a little floody if he wants more focused.
Sofirn sp35 and Thrunite T2 have good sustained output (especially the T2!) but both have usb charging.
What about rotary or ring control lights, such as sofirn SD05? Too big?
My brother believes tools should be able to survive abuse or they aren’t good tools. For that reason I am thinking of starting him off with something cheaper than the sc700d. I don’t like the sawtooth ATR on the SP35 but like you said, both have big rubber plug charging ports so I guess the point is moot.
The SD05 looks alright in terms of size and output. I am not sure what he would think of the ring interface though. If it was a ring with an on/off button I’d buy it confidently. I do wish it had a little knurling too. Maybe it’s a diver requirement but I think it makes it look cheaper.
Not perfect for the criteria, but how about:
- Olight Seeker 2
Get one with USB charging, remove the rubber boot and fill it with a hot glue gun.
You’ll never be able to remove the stuff to use the USB but it will be very waterproof 
IF22A with a glued port?
A diving light like the Wurkkos DL30 checks all your requirements
https://wurkkos.com/products/dl30-21700-diving-flashlight-3600lm-triple-lh351d-high-cri-magnetic-control-ring-switch?VariantsId=10015
The Convoy M3 without onboard charging is still available.
Solarforce L2.
It’s 18650, but cells are much cheaper and easier to get. Very tough light. I carry it in my toolbox, hits floor many times, still works perfect.
Mike
Maybe the Astrolux ST01. Might still have the discount code on here in the introductory post a few months back. Has usb charging but the button aux lighting is unobtrusive and useful (low volt, lockout…only, I think). Stout dual springs in the tail, which is good, but brass button on the driver instead of a spring. For the usb port, you can remove the cover if it gets in the way in darkness, or trim the top off smooooth with a razor blade (filling the area seems drastic and could be a problem if you ever need to replace the driver).
Is this indoor or outdoor use? If it’s indoor just give him a convoy S2+ SST 20 4000k or a wurkkos fc11 in 4000k. What exactly is he using now? I seriously question his list of requirements. Is he going to carry it on his person or in a bag or other?