Basically, VG is for cloud and PG is for throat hit.
Also, VG makes the juice thicker (more difficult to wick on a tank) and PG generally gives better flavor.
Some people is allergy to PG but there are people like me finding VG more irritating than PG (my throat feel very uncomfortable when vaping a high VG% juice)....
I suggest you order both high VG (70% VG or higher ) and some normal (50% VG) with same nicotine level to find out what you prefer.