its quite a tricky question to me because i carry 16340 format when off duty, whenever i feel relaxed and carry 18650 for duty and performance.
18650 by far, sick of AA and those horrible AAA’s.
I use single cell 18650 lights mostly now, one CH10 headlamp and one C8 style are my go to lamps. Still have a few AA lights around though, just not interested in buying anymore in AA format.
Definitely 18650, the energy density is far superior to AA, and the Convoy 18650 tube lights (and equivalent) have a surprisingly small footprint.
AA for me, Eneloops in my EDC, Nitecore MT2A.
It has to be a single cell AA.
Li-ion is for serious output, which I just dont need for my edc……but I do “need” for my other lights 
AAA for me. I keep a small twisty light on my keychain for convenience.
16340 followed by 16650.
I’ve been told that, in the event of an emergency, and I’m talking city/county/state-level emergency here, the National Guard will be handing out AA batteries like candy, so that’s what I tend to favor. I have a soft spot for tiny little AAA lights and 10180 keychain lights, but I generally get AA if I’m going to spend money.
I carry a 18650, and a AAA light every day. And for head lamps I have two either a 18650, or a 3 AAA one. I picked 18650 on the poll.
I still tend to use my J18 the most frequently of all my lights, and I still probably empty 26650s more frequently than 18650s, but I guess I’d have to choose 18650 since I cant fit my J18 in my pocket.
AAs and AAAs are for remote controls, clocks, monitoring devices and Wii, etc.
DQG tiny 26650 anyone ?
Mostly I carry a 502B with a 18650 laptop pull. When weather is extremely hot or I need to carry something smaller then It’s a single AA Eneloop in a small inexpensive zoomy.
I voted 18650.
Currently I have one on my key chain that uses a BLF Tiny12 driver with two stacked 7135 chips. It draws a constant 0.7 A into an XP-E.
I have others that draw 1.5 to 2 amps., but not regulated or controlled. I also carry a Pakistani two blade pocket knife. They both need renewing now and then, but I have time and like to do it.
Convoy S8 - so 18650
I have some 16340 lights - but they are too small so hold comfortably (I have big hands).
16340 for me, just like my finger, short and fatty.
16340. My EDC gets many short uses during the day so runtime is not an issue, while pocketability is, I carry the smallest possible 16340 light (but with dedomed N219b@2A for a bit of throw).
I’m always wearing skinny fit jeans so pocketability is a bit issue for me, 18650 is a no no. For this reason I carry 602C with triple 219A with Qlite 10 x 7135s. For around house I found SF-348 with 219A to be the best because for up to 3 meters use all I need is 30ish lumens high CRI single mode light.
Did you have to shave a lot off the triple optic and ledboard to fit it in a 602C? Do you have a picture, I'm really curious?
(sorry for the off-topic question)
They have a new 18350 Convoy S2+ and it’s very nice 
You need to shave 2mm or so from optics and star.I’ve used noctigon mcpcb and optics from triple nichia bundle from Kaidomain. Optics are not direct swap becase legs are wider than Carclo ones so you need to open up the holes on mcpcb. You also need to shave the pill because whole assembly is too short so you need spacer between mcpcb and pill. Spacer I made is only 1mm thick because I used 1.5mm AR lens. I didn’t used 18mm ones because I also filed down the lip on the head because I didn’t feel comfortable with fact that there is too much light looses with already “weak” nichias combined with “unsuitable” body for triple setup. Instead I used 20mm lens that I also shaved down 1.something mm. I will ad pictures later today