HD2010 has a larger 57mm reflector and more massive body, can use 26650, cost ~$30.
C8 fits in a largish pocket, ~42mm reflector, ~$10 plus $~2.5 if you want a smooth reflector.
Mod hd2010 throws more; stock SMO reflector vs stock C8 OP reflector.
All depends what you want.
I’m a chip stacker, Please make mine deeper so I can maximize output. Thanks, and thanks Tom for making the suggestion!! 
Just ran into that last night, had a driver ready to go and it wouldn’t fit, have to do some work to remove copper to get the double stack of chips inside. 
This is a couple of 1/4” thick copper rounds put into an M8 pill and re-flowed into place utilizing the brass press fit sleeve that originally held the driver. Ended up breaking a new driver with the Zener mod by breaking off the positive lead and it stripped the solder pad when it went. Nothing left to solder to in order to fix it. Always something! lol That’s what I get for trying to force an issue. Live and learn.
I would recommend the HD2010 if you haven’t got a larger reflector thrower already. Also you’ll probably see more benefit from the copper pill there, just in terms of being able to drive it harder.
It’s a great thrower with a nice reflector but considerably larger and heavier than the C8.
I probably will go with the c8 as I have enough bulky throwers already like the zyt13 which I don’t use because of the length and the c8 I have fits easyly in my jacket…
Thanks for the info the convoy c8 host is indeed just 10$ so this will be a real budget light.
Edit:
What a nice form you have made, thumbs up.
Paypal for one c8 pill sent
Thanks for the smooth reflector link. I put a convoy in my cart yesterday, and didn’t even look at the reflector type.
What about this reflector?
https://www.fasttech.com/p/1220100
I ask because I have laying it around…
Paypal sent for 1 * HD2010 pill with tracking, plus some change for your efforts.
Please supply deeper option suitable for chip-stacking.
Cheers. 
I’m a stacker, too.
Please add my HD2010 pill to the list with more driver space.
TomE is right, don’t raise the LED base too much. Raising is good, but not too much. If you raise it 1mm and add a Noctigon 20mm star, there is hardly any space between reflector and star, risking short or destroying the solder pads on the noctigon when fastening the reflector. 0.5mm sounds good.
Accordingly I do not recommend pulling the threads up completely (Post #136).
Admittedly this might increase the contact surface between pill and body a bit, but the small space is for an o-ring which, in addition to its usual purpose, can help tremendously to adjust the pill to the reflector. You can screw in the pill as much as you want to adjust the height and it always sits tight, putting pressure on the threads, which is good for the thermal transfer where it is needed most.
Thanks for your effort in this.
HQ
Oh fair point on the pill o-ring groove. Both of my HD2010s (Fandyfire and unmarked Tmart ) didn’t come with an o-ring installed so I didn’t even consider that.
Is it just the original genuine Ultrafires that came with that o-ring installed?
I don't know, I posted the one Geek suggested here.
http://www.fasttech.com/forums/1277302/t/1001903/smo-reflector
I find it easier to sand the pill down than to find a peice of copper to place under the pill to raise it up, and yet another thermal break, but every .5mm higher helps
Chris
It’s chinese lottery, I believe…
But both my HD2010s came with an o-ring at that place. First one a grey Tmart, marked only Cree XM-LT6, some 6 months ago, and second one the black Fasttech Fandyfire, 2 weeks old. The Tmart o-ring broke at first disassembly, the Fasttech one survived.
Tmart light was bad in many ways. Emitter horribly off-center, driver gave spectacular 1.1 A on high… Was meant as a host anyway, so no harm done. My Fasttech one is better, driver centered, direct drive on high with 4.8A at the tailcap with full Enerpower 26650 4500mAh. Nice throw.
Lottery is right, or rather a crap shoot…I have the same two brands/makes you have except with exactly the opposite opinion of the two. My generic T-mart one was great (albeit black instead of the grey I ordered) and the Fandyfire was rather disappointing (thicker and bigger opening in reflector, off center led, deep led centering ring led etc). It’s very hard to get a good beam profile on that one.
Can be very annoying when you don’t know what to expect.
Is anyone still selling a good grey original HD2010 with Ultrafire branding?
I was thinking about AMC stacking, but I just got my very first HD2010 in the mail today. It’s a Tangsfire, and it’s giving me a tail reading of 5.3A right out of the box. I don’t think I’ll be switching drivers.
I’m guessing FT took it off their site? Nevermind, they list it as hd2010 without a space.
I don’t want to derail the thread but does anyone have experience with the Rustu branded version of the HD2010 available from DX
RUSTU R41H
Well, it says the circuit is 1A, and actual lumens are only 388.
Circuitry: 1000mA
Brightness: 900lm (manufacturer rated, actual 388lm)
I don’t know if the actual circuit is 1A and high is direct drive, but 388lumens is pretty low.
Yeah not too worried about the driver and emitter, they’ll be replaced anyway.
I’m just looking for a nice quality grey HD2010 host really.