It all depends what you're trying to do. I have both and honestly only use my MVP2 w/PT2 for road trips (don't drip and drive people!). Sub ohm vaping with a dripper, for me, is far superior to anything I have experienced with a VV device. Even if I build a higher ohm coil to run on the MVP or Zmax. The 11 watts that the MVP puts out is just not strong enough, IMO, for a RDA. The 15 watts the Zmax puts out is a lot better but still a little too cool of a vape for my liking.
With all that being said, if I had to choose between a mech or a VV device I would go with a mech, simply because of the durability and reliability of it. But, I also understand battery limitations, ohms law, and have a digital multi meter that I use every time I change the cotton out....safety first. And its not overdrawing the battery because of a low ohm coil that I'm worried about, its those damn hard shorts!
Although, I am thinking about purchasing a DNA 20 mod. 20 watts of power...mmmmmm. Its either that or a ReoGrand...decisions decisions.