14500 is my preference … 
Lumintop tool AA and AAA
I like more the 14500 format because most of them can run also with regular AA 1.2/1.5v
14500, 18350 and 16340 are quite “fat”
id like to see the 18350 gain some more steam, an olight s1r with an 18350 would be interesting…
Well, happily there are some 14500s quite “slim” 
Pun intended
I think you and mrheosuper are in agreement. I agree as well, 14500 is my first choice for EDC because it is slimmer than the others. But I also like 18350 and 16340 size lights.
What is the light on the left?
Where’s the button for AAA? 
@ DavidEF
The one in the middle is a 14500 light, a DQG Slim Ti So I wanted to show that some AAA lights , such as the Olight I3T EOS (right) and a generic 2€ Zoomie from a Chinese store, are bigger (although a bit “slimmer”) than the DQG
@ Agro
It is cheappo light, a zoomie one ! Bought it in chinese store as I wanted to mod it but…I’ll let it go! 1 mode, put an XPG2 inside only and I call it a go 
EDIT: Stooopid me, only now I notice that the “,” (comma) was indicating the answer and not an enumeration :person_facepalming:
I get what you say now, DavidEF
DQG Slim! Ah, I missed the joke! 
AAA.
I also like AA but consider that medium sized.
I don’t normally need big lumens from smaller lights. So I prefer nimh for availability, cost, and stability.
x2
I had a dream about an AAA size RRT-01 with LVP, then I woke up to my Phat TCR-1 with an unprotected 18350…
The perfect light is a combination of features, none of which exist in any one model.
Same as Women.
I like to have more than one.
.
Does Size Matter?
from shortest to longest:
short and skinny: ET 16340 2.9”
longer and fatter: RRT-01 18350 3.2”
long and skinny: ET AA 3.4”
Four of my favorite small cell pocket lights.
LAN Mokume Gane XP-L HI 5000K, 14500, Electronic Tail Switch.
FourSevens Atom XHP50.2 3v 2A, 16340, Reverse Clicky Tail Switch.
CRX CuTi Zoomie KW CSLNM1.TG, 18350, Forward Clicky Switch.
CRX Rotary XP-L-HI 5000K, 18350, Rotary Lighted Tail Switch.
Definitely 14500
14500 for the same reason as everyone else - slim. I would’ve thought 18350 got more votes for drain rate and capacity but there you go…
14500 lights are my choice. I like the slim profile.
14500. Because its slim and the ability to swap out with a AA.
For the last few years, it’s been the EagleTac 2014 D-25 25 ti. clickly.
Chris