I have a nemesis, sentinel m16, and origin clone all from hcigar. Out of the three, I prefer the m16. It has a sturdier construction (dislike the flimsy lock ring on the nemesis, otherwise it would be my favorite) but in 18650 mode you can see the threading on the inner tube, which bugs me too, just not as much as the lock ring on the nemesis. Very small and beefy in 18350 mode.
The origin is very light weight but I do not like the locking ring on it. Also, the tubes don't go together as seamlessly as on the nemesis, and it is 21ml in diameter so there aren't a whole lot of toppers that sit flush with it.