Oftentimes people like at least some VG for the "lung hit", the extra vapor production adds something for them.
Myself, I can vape anywhere from 0PG to 0VG, and do so, since I DIY and make some liquid that I share with others.
Some people are sensitive to PG, others are sensitive to VG, reactions ranging from general irritation to breaking out in hives. (Hives are an edge condition, not common, and at that point it is also at least moderately possible that a person may be allergic to a given flavoring, rather than the PG or VG).
A nominal 80% PG, 20% VG is pretty popular, a nice mix of PG and VG properties. For myself, less concerned about TH per-se, and since I use a mod that cranks the power (inherently more TH), I tend towards 65% PG on my own liquid; too high on the VG and I feel slightly sluggish when running (it's my personal perception, not necessarily the same for anyone else), though I appreciate a decent amount of vapor.