Consistency is huge for me, the VVG stays spot on right up until it's time for a battery change, which is, for me, after around 6 ml (a full bottle) of vaping. (I vape in the 8 - 10W zone, 4.5 - 5V with a 2.5 ohm carto or atty)
Unregulated standard Grand wins for raw simplicity, durability (VVG is rugged, but it does have electronics), but over the course of use the nominal voltage will vary from a starting point of about 4.2V and drift gradually down, until you change the battery. If you vape to the point where the battery output is 3.5V, and started with a 1.8 ohm atty, power will be going from 9.8W down to 6.8W over the course of use, a pretty healthy change. You certainly can minimize the change by changing batteries more frequently, at higher voltage, just depends on the degree of hassle.
VVG if set to 4.9V output on a 2.5 ohm atty stays right there, all day, no drift. If you decide during the day that you want a little less oomph, you get to turn the voltage down slightly. Likewise you can choose to adjust voltage up a bit for a warmer vape.
Both are excellent, but if you are used to being able to change voltage when you want, control the vape, VVG is where it's at