I'm going to sound like a database admin for a second, but the real answer is "it depends".
PG/VG mix preference - for those who don't have an allergy or sensitivity to either of them - is a balancing act between throat hit, viscosity, and vapor cloud. And how it behaves is also dependent on the gear you are using, ambient temperature, and, in my experience, also to what flavoring you use.
That said, most of my MBV juice is 65/35 +1. In the summer, I discovered that any more VG than that = higher potential for leaky gear, because the VG definitely thins out more when heated than the PG does. (50/50 on already thin juice was a really bad idea...)
I also steath vape alot - which means I'm going to favor higher PG juices to keep the vapor production down.
The odd thing? Some of my 65/35's produce far more vapor than others do. I can only put that down to differences in the flavorings themselves.
Best thing to do is buy in small quantities and experiment. Figure out where the sweet spot for you preferences and gear is, and be prepared to adjust as needed.
<glances at juice stash>
Of course, I don't think I'll be *able* to adjust for at least a year...
Seriously, though, if you decide you want to adjust the pg/vg balance in juice you already have, you can buy either 100% PG or max VG in the same flavor, and mix it with the juice you already have. That will let you adjust it if you decide, for example, you want to flip from 80/20 to 20/80, or so.