My most used is the nightcore keyring light. It's old so has micro USB but I'm sure the new ones will come with usb-c.

I'm not very happy with my fenix AA LD12 as when the battery gets low it dies suddenly rather than dims out.

Good flashlights usually don't have adjustable beams. Zoom mechanisms are bulky, optically inefficient, and aren't very durable or waterproof.

The Acebeam EC35 II or T36 would be exactly what you're looking for if you could get one. Unfortunately both are discontinued. If the Acebeam L16 2.0 isn't too fat to put in your pocket in a pinch, that might work.

I'm going to suggest a headlamp instead of a handheld flashlight since it's incredibly useful to not have to hold the light to see what you are doing. And you can always hold it in your hand and use it as a flashlight. Particularly, while I realize that the price is outside the range you said (it's a heck of a lot lower), I think the Wurkkos (Boruit?) H25S is an incredible value at $15 shipped (FIFTEEN DOLLARS):

https://wurkkos.com/products/d25s-waterproof-headlamp-18650-headlight

It has 1200 lumens, 4 levels, fairly sane UI, USB-C charging, and uses an 18650 cell included with the light. I have the H25LR version (similar but has a 500 lumen white led and a night vision red led, instead of two 500 lumen white leds) and reviewed it here: https://lemmy.world/post/22928160

I use it all the time, it's solid, or if you're worried about reliability then heck, buy five of them and have $$ left over from your $100. There are a bunch of other variants too, though I don't know exactly what the differences are.

Obviously you can find more expensive headlamps if that's what you really want, but there is not any need imho.

I also like the HD10 which runs Anduril and is smaller, but it uses a 14500 cell with much less capacity.

Of all the flashlights I own, one of two is always with me:

• OLight Arcfield Pro. It's chonky and uses that OLight proprietary magnetic charger, and no USB-C. However, I carry out around the house, use it all the time, and charge it maybe once a year. I'm not exaggerating. Seriously, I sometimes think it has some perpetual energy device in it, but probably the battery is simply massive. Using the blacklight sucks the battery down, but using the laser and regular white light LEDs it just lasts forever. There's no noticeable passive drain over time, either. At just under $100, if I could have only one flashlight, it'd be this. It is still comfortable to carry in jeans, and I've left home with it forgetting it was in my pocket, but I generally don't like to have a lot of stuff in my pockets. So,
• the second is an EDC, and is currently in one of my pants pockets somewhere. It's one of those little Rovyvon (or knock off, or one Rovyvon knocked off) keychain lights. It's a metal (titanium?) body but has RGB LEDs in the body, which makes me think it's not a Rovyvon because I think all of their's like that are clear plastic bodies; but it's of that design. Acebeam makes one almost indistinguishable, IIRC. USBC charged, and it fits in a jeans coinpouch; it's even small enough to fit in a standard women's jeans pocket! The battery lasts a long time and also has imperceptible battery drain, and I don't fret about keeping it charged; the battery indicator gives plenty of warning, good for another night's use before going empty. That's around $60.

Now I have to go digging and find the keychain light; usually I keep it on my valet, but I sometimes forget to empty my pockets and especially the coin pouch, which is where I usually carry it.

Honestly, I could probably get rid of every other flashlight and keep just those two; they're the only two I ever use.