Some of the top rated (and favorite) PVs are
Provari
Mini Provari
Buzz Pro and Ipro
also the
vv madvapes box mod is very reasonably priced and works great.
The Provape Provari and the Provari mini has a readout that shows voltage, batt life and atty/carto ohms and uses one 18650, 18490 and/or 18350 batt
The Notcigs Buzz Pro and the Ipro has a wheel that you use to adjust voltage up and down and uses two 18350 stacked batts.
The madvapes vv box has a voltage readout window also but doesn't show batt life or atty/carto ohms.. it's very easy to cut on and off though. It uses two 14500 batts side by side.
There is the
VVPV by not cigs, it's a vv box that instead of feeding from the bottom, has a tube which feeds juice down into the atty. It comes as a kit including batts and a charger. It has been getting rave reviews also. It uses two 14500 batts side by side and (I think) can be charged while they are inside of it.
All of these devices are sold by reputable vendors and are good values for the money if you are serious about vaping. They are also reputable as having built-in safety features.
If you are interested in bottom feeding.. there are several good modder sites out there. I have the
VV Reo Woodvil.. the VV Reo Grands will be going on sale June 12th. They work great. Handmade wooden box mods are expensive and are also considered (by many) to be show pieces. I always wanted a Reo (but didn't want to pay that much for unregulated 3.7v) and and a Buzz Pro (but I chose a provari instead) so when the VV Reos came out combining the bottom feeding form of the Reo with the VV Buzz electronics.. I had to get one.. I figured it was like getting both devices in one package

But like I said, there are other VV bottom feeders out there..
Bogger's box mods is a VV box that gets very good reviews.