Vapor DOES play a role...but also depends on "what" vapor. VG will smooth it out and add vapor, pg is raspy, light vapor. But its ultimately the combo of the pg/vg, nic, flavor, then unit, that determines what you experience. So many variables, but they all play a role.
So Phil is right AND wrong. All things being equal, you'll see lots more vapor, but lower TH and flavor from 100% vg. Less vapor, but more TH and flavor from 100% pg.
But its is a psychological thing behind what ppl desire, as your looking for the right COMBO of performances, not just a single aspect. Mine happens to be 80/20 mix with 24mg on standard 510 setups, or 18mg on LR setups/mods. Both give similar experiences for me. The 80/20 makes for right vapor level,(though not quite as much on the standard setups as LR) but the nic makes majority of TH, that I find more important.
100%pg doesnt satisfy my desire for exhale vapor, and doesnt fulfill the thickness of vapor either. But 100% VG is too silky, and pulls away from the nic hit and flavor too much. So 80/20 was the right combo for me.
Its a mouthful there, but not as complicated at it sounds.
But these variances are why you'll see some vendors like kick bass or Mrs. T's doing 60/40 mixes ( I think), while others like johnsons creek do 100% pg lines, or uses 10 or 20% flavor, etc. It all caters to what certain vapors desire. But each company will generally start up creating the mixes they prefer personally, then grow a fan base- based on customers similar desires for their liquids.
Each company having their own "way" about liquids is what separates them. And its a good thing in the end...because the only variance left would be price. It sucks having to search out the company profile you like the most personally, but once you have found it...well, you found it.
This is also why you take reviews with a grain of salt, and why its best that the reviewer understand and reveal their personal preferences when it comes to liquids, up front.