Temperature control and user interface.
I wanted a dual battery temperature control mod that could go up to 100W at least. My Freemax Starre works great at 70W and I wanted some headroom above that. I also wanted a temperature control mod, and I wanted a very easy to use mod that didn't require me to spend long periods fiddling with menus before I could use it whenever I changed attys.
The SnowWolf 200W delivered what I wanted. Dual battery, will work just fine at 70W with plenty of headroom so I'm not pushing the batteries or circuitry to the limits, it has temperature control, and a menu-less user interface. When I put a new atty on it asks "New Atomizer?" and I press the + button for yes, then it detects the coil resistance and automatically selects either wattage or temperature control depending on the coil type. I switch between setting the wattage and setting the temperature by pressing both the + and - buttons at the same time. That's all there is to it. Fast, simple, and very user friendly. I love it.
The fact that it does 200W is irrelevant to me. That wasn't a selling point, but I'm not going to turn down a mod that does everything I want just because it has the option of delivering more power than I'll actually use.