Well I guess Single Ladies. It has higher digital sales, is considered one of the biggest dance crazes of this millennium, has far more iconic choreography etc...
Toxic is a cute hit but I don't see it beating single ladies cultural impact in any respect
That is why its about to become one of the 5 oldest videos by females to become #VEVOcertified, right?
This.
Single Ladies has been forgotten, it was uploaded when it was released and has just over 200 million views while Toxic was put on YouTube 5 years after it's release when supposedly everyone had "forgotten it existed" and has still managed to garner 100 million views, when it had no promotion or anything.