Well there are plenty of recent threads that have discussed this a lot. In brief, its a matter of preference. VW is more convenient. As one person posted, its like having cruise control.
Variable watts is not new. Variable wattage has been around for quite a while now. The Darwin is a variable wattage mod. However they are virtually impossible to get. A lot of vapers added variable wattage to their pvs by using the Kick - a small piece of circuitry that can be put on top of a battery. Having variable volts and variable watts on the same pv is new tho.
For myself, I prefer variable wattage over variable voltage because I can switch from one accessory to another and stay at the same watts. Or I can adjust watts and not worry about calculating whether the volts are ok with the ohms - the device adjusts the volts automatically to the right level.
I can also adjust watts with different juices, and again not worry about volts and ohms being mismatched since it adjusts the volts automatically. Since I have a lot of different juices this works well for me. Sometimes I just change the watts with the same
juice - depending whether I want it a little cooler, or I feel like getting the warmer taste. I like some juices at more than one temperature. So I adjust the watts, which is the power, with a simple click or two and vape.
I think this is an exciting time to be a vaper - there are new things coming out to try and we have a lot of variety. The new eVic is is causing a bit of buzz because as well as having vv/vw it has software functions as well.