I'll credit Train2 because I asked the same question a few days ago (so now I'm an expert..lol). Here was Train2's reply:
It's a bit of a trade-off. Presuming no allergy either way, here are the + and -
PG+ better at carrying flavor
PG+ better at carrying TH
PG+/- thinner, too much and may cause leaks/too little and thick juice may not wick to the coil
VG+/- thicker, too much and thick juice may not wick well, too little and thin juice may leak
VG+ better at producing vapor
So try a couple ratios and decide what you like!
I've started to DIY, so I can make something 50/50, and then next time if I think i want a little more vapor to it, could make it 43/57 if I want to...