It all depends on the features you need. Some are so different from one another that you might need to break it down in to categories. Features go well beyond just the form factor of box or tube. Catch cup - juice well - connector type - connector quality - ego friendly connector - raised connector - sunken connector - feeder - non feeder - mechanical feed - pump feed - top feed - bottom feed - VV - VW - build material - size - weight - etc etc etc etc. Without knowing what features are important to you, answering the question "what pv is the best?" is not really possible.
I really think that concentrating on a single feature (in your case, you asked what is the best VV device) can be a mistake. There are lots of different kinds of VV devices and a plethora of different features to think about.
Personally, I've come to the conclusion that I'm unlikely to buy anything that isn't a feeder from now on. The feature "feeder" and the feature "high quality 510 connector" are the two things I look for first now. After that, I start considering feed type, build material, price, and voltage regulation (pretty much in that order). There are quite a few high end feeders. The two I decided to own are the VVPV and the REO VV Woodville. I am also likely to get a REO VV Grand in a couple of weeks when they come out.