Although I have only used the JoyE 510 Pass Through I think I would have to say it is the most recommended for those just starting to use personal vaporizers (i.e. electronic cigarettes) I like the pass through so I could see where using the normal batteries would be good, especially for the new vaper (person who vapes instead of smokes).
I can't say that it is "officially the best" because everyone will have a different opinion and there are so many different styles of PV's out there.
The JoyE 510 is a lower voltage (3.7V) device and a lot of folks enjoy a higher (5V-6V) vaping experience like myself.
Again though if we are talking about recommending an electronic cigarette to someone who has never used one, I would have to say that for the price/quality of product/vaping experience I would probably recommend the Joye510. This way for an affordable price someone can experience vaping before investing in a more expensive PV kit or mod.
UPDATE: Since originally posting this in Mid 2010 I have purchased and used the prodigy V3, and the JoyE Ego. The JoyE ego has a 510 connection and I've discovered, at least for me, the Ego with a low resistance 510 cartomizer hits the sweet spots of throat hit vs. flavor vs. stiffness of drag.