For the Nemisis my first choice is the Genuine
Evolv Kick 2
While the Evolv Kick cost a little more here's why.
1. It's the most powerful regulator in its class, from 5 to 15 watts (the clones top out at 10 or 12 watts).
2. It offers a sub-ohm mode. This means if you've the right batteries, you can use atties as low as 0.5 Ohms and still get the thermal, short circuit, and over drain protection. Note that in this mode you won't be able to buck to lower wattage, but then again if you're going to the trouble to sub-ohm then you're looking for the highest wattage possible. None of the clones will do this.
3. It's built better...with dual gold plated spring pins making contact to the inner sleeve of your mod. Evolv is US based and has a good reputation for quality customer service.
4. DC signal that is solid and steady. (No rattle snake PWM stuff).
My second choice for a Nemisis style mod is the
Artisan Crown 2.0.
The big plus of this regulator is that you can adjust it without opening the mod and using some tool to turn a pot. You adjust it by a series of short and long presses to the mod's main fire button (it beeps and sings to you for user feedback). Like the Evolv Kick...the Crown also uses DC circuitry, and provides similar safety features. It also comes with a magnetized PTC fuse (optional with telescoping or spring loaded mods, but used as an extender with the Nemisis). Where it falls short of the Evolv Kick 2 is that it can't do sub Ohm atties. The VW mode doesn't have as much resolution as the Evolv Kick (setting fractions of watts). In VW mode, the Crown tops out at 10 watts; however, there is an interesting plus. It can also be used in VV mode from 3.5v to 5.5v (0.2v increments), so with the right resistance atty it's possible to get up to 15 watts (maybe even beyond).
With a Nemisis, it's really easy to get to a Kick 2 for adjustments, just take off the top most cap and the pot is right there for adjustment (but you'll still need a tool to turn the pot)...so...the Kick 2 cost a little more and offers more VW power and resolution for the money. The Crown costs a little less, has the added benefit of button pushes to adjust it, but isn't quite as powerful/versatile when it comes to VW power range and atomizer resistance choices.
The clones from Smoktech and Segelie can be found for half the price of the two mentioned above. They generally regulate from 5 to 12 watts. They use a pot to adjust like the Evolv Kick. Some of them are said to use PWM instead of DC, which means they might have a bit of a rattlesnake sound when using them.
I've used Evolv Kicks and Artisan Crowns for a long time now. Both have held up and perform really well. I find battery life between charges to be similar for all my Kicks and Crowns when comparing similar settings. I tend to use the Kick in the Nemisis like stuff (where the top screws off) and I drop the Crowns in mods where it's a bit more of a pain to fish out the regulator for adjustments (Only the bottom comes off).