1. The Comparison as Searched Is Slightly the Wrong Question
Setting PRP against microneedling frames them as two options on the same menu, and that framing quietly misleads, because they are not the same kind of thing. Microneedling is a delivery method. A motorized handpiece drives fine needles into the skin, creating thousands of controlled channels and provoking a healing response in the tissue around them. PRP is a substance. It is platelet rich plasma, drawn from your own blood and concentrated before it is put back.
One of them is a way of getting somewhere. The other is something you can bring along. That is exactly why the two are so often used together rather than chosen between, and the marketing name vampire facial describes that pairing and nothing more exotic: microneedling with PRP added to it.
So the real decision is narrower than the search term suggests. You are rarely choosing PRP instead of microneedling. You are usually choosing between microneedling on its own and microneedling with PRP added, and that reduces to two practical questions. What does the addition cost, and what does the addition buy.
PRP does have uses that involve no microneedling at all, most commonly injection into the scalp for hair thinning. That is a different treatment answering a different complaint, and it is worth separating from the facial question.