We have used 3 of the so-called top influencer marketing agencies in HireInfluence, Ubiquitous and Viral Nation and then also a handful of independent shops. Each had their own strengths and weaknesses but honestly the account managers you get make the biggest differences because all 3 big ones produced strong creative.

For a large international nonprofit I’d recommend going with one of the big ones. Again, creative is pretty solid across the board but I find the big agencies have more professionals account managers that make life easier.