According to Netflix, Stranger Things has been viewed more than any other series or film.
Monopoly Stranger Things Edition
Netflix claims the popular sci-fi show was viewed in over 40 million households since it was released on July 4, 2019.
I find it interesting that Netflix does not share their streaming analytics publicly and only share statistics of their shows when the number really great. Stranger Things is one of better original Netflix creations and it has a cult-like following. So I am not sure what Netflix gets out of telling us Stranger Things was watched a lot within the first few days of its debut.
Stranger Things: Worlds Turned Upside Down: The Official Behind-the-Scenes Companion