Who is no. 1 direct selling?
In direct selling (a distinct category from marketing agencies: think MLM, party plan, network marketing), Amway consistently ranks as the #1 direct-selling company globally by revenue, followed by Natura & Co, Herbalife, Vorwerk, and Nu Skin. This is off-topic for the growth-services directory but appears in "marketing agency" search results due to ambiguity.
This question turns on judgment rather than on vendor data. The Wall's index holds no figure that bears on it, so none is attached. The answer above is editorial.
Why this matters
Google puts this question in People Also Ask for the "marketing agency" query, which means buyers are asking it while they shop. The answer above is The Wall's editorial position. We index 3,460 verified US growth-services vendors across 10 pillars, and this particular question sits outside what that data can settle.
If you are evaluating vendors in this category, the Marketing pillar page carries the full US firm list with rate, team size and headquarters filters.