Ohms Law
P = V²/R
Power and Voltage are related. The beauty of variable power is that no matter what resistance atomizer you put on it, it will always output the same power by adjusting voltage to compensate. There is no difference between the two given the same resistance and power/voltage setting (i.e. with a 2-ohm coil, setting either 4V or 8W, it's the same thing).
That being said, what amount of heat at the coil is better depends completely on your
vaping preferences and the
juice you're using. Just play around with it and see what tastes better to YOU. There is no magic setting, and one person's preferences may not be the same as another's.
I'm telling you this now so you get the best vape to YOU rather than wasting time and money chasing after someone else's perceived success. You can spend a lot of time and a lot of money trying to pursue a vape that will never exist for you given someone else's setup.
Anyway, to stay on topic, I prefer my vape around 8-9 watts, depending on the juice, when using a VV/VW mod. I suggest you start at 8 and adjust to taste.