What’s the best source of protein for building muscle – meat or plants?

Citation

Witard O, Tipton K & Hamilton DL (2017) What’s the best source of protein for building muscle – meat or plants?. The Conversation. 31.03.2017. https://theconversation.com/whats-the-best-source-of-protein-for-building-muscle-meat-or-plants-75330

Abstract
First paragraph: Do vegan bodybuilders have the edge? A recent study was reported as showing plant-based protein was more effective for building muscle than that from animals.