Of all your lights, which one gets used the most and why?
It doesn't have to be your favorite, your edc, your most expensive, etc.
Currently, my most used light is the UniqueFire 2100 because it's new to me, is very bright and with fall/winter coming, makes a great handwarmer. ;)
That said:
Fusion 36 dropin in a 3D Mag for dog spotting. It really needs 4 cells to give of its best but the 3D is what was lying around.
FandyFire triple XM-L. Assistant spotting when the Fusion doesn't do it.
Zebralight H50 (Q5). Most used of all the lights i own and has been since i bought it five or so years ago.
Mr.Lite J4 XM-L and reflector modded. Sometimes I use the BLF edtion version with a body bored for a 17500. Black body but silver head and tail - the silver head has the XM-L in it.
+1 :)
My most used flashlight has to be the quark 1232 mainly because it is always on my person. Most recently is would also be the UF-2100, also because it is new to me and it is small enough to carry. Did I mention it is bright as hell!
UF-H2. Smooth flood is just a more functional beam for working on things in the dark. And it's small enough to compfortably keep in the pocket. If only it were NW tint.
Zebralight H51f or ITP A3...it varies between the two.
I lost my A3 on Sunday night in the local swamp park. Not been able to find it since.
:-(
My edc varies so its not that. So its probably my 502B with a 1A driver feeding an XP-G R5. I seem to pick it up and pocket it whenever I go into the garden. (Although I usually take some other random light with me as well......
Zebralight SC51. Small, bright, good UI, useful clip, it's always with me.
DQG Tiny II R4: Always with me, in the same pocket than my house / car keys.
At the moment, UF 2100 single mode and Palight T6 for the same reasons: they are new and bright. And I like new toys. :D
But that's just the last couple of weeks. My other go-to lights are the KD C8 I keep in my car, my SF l2m with the ever popular MF 3-mode XML drop-in and the Skyray S1 I use as my keychain light. That pretty much covers 80% of what I use.
Workhorse: L2m with extender.
Then Sc51w and latest DQG Tiny II.
i always use my keychain light the most. right now it's a Fenix E05.
My most used (most time on) is the Manta Ray XM-L C8 (from KD) that I use for my regular night walks. For that task it has the perfect beam profile, the right brightness (at 440mA Mid, regulated) and adequate runtime.
In the back pocket I also carry one of my throwers, to spot animals (i.e. avoid the occasional bear 
), but these are used for short bursts.
Most used by far: Sipik SK68 - love it with the 14500 AND I love it with old already used up AA´s since the driver can utilize them down to a ridiculous low low moon kind of low. And that rocks!
I hate to admit it but the UFH2 and my beater X2000 that I use working on cars gets the most use.
Sometimes it isn't the most glamorous light that's the most useful. Try using a 3*XML under the hood.
I'd say my Fenix LD15 because i have it with me all the time.
I wouldn't want treat my triple X lights like the X2000. I have no hesitation using it for a hammer or getting grease all over it and the zoom is priceless for finding lost screws or looking in spark plug holes.
It's my Itp A3 since its with me all the time