PG is thin and lets through the most flavor, most nicotine TH, most nicotine irritation but makes thin visible vapor that disappears quickly
VG is thick and dulls everything PG lets through but makes nice thick vapor that hangs around longer
Most people use blends. IMO the optional blends for various methods...
Atomizer + drip tip or cart: Anything works as long as it flows at least as fast as your vape it
Simple stuffing cartomizer: I find 20% or less VG keeps the carto working well longer - good wicking, good drag
Dual coil carto: (these are for big 450mah+ models only due to the intense power use of 2
coils) Some say they can vape up to 100% VG in these but you may expect shorter use out of each carto
Reservoir cartos and
tanks - these like the thickness for 20-30% VG and less will work but may leak more easily. Some thinner 50/50's may work.
NEITHER PG nor VG is harsh. NICOTINE is what is harsh.