So far, after appropriate adjustments, Black Panther is running about 10% behind The Avengers 1. That’s really good (obviously) and would put it 6th overall for superhero movies if it stays that way for its run after:

Superman 1 (1978)
Batman (1989)
Avengers 1 (2012)
Batman: The Dark Knight (2008)
Spider-Man 1 (2002)

(All grosses adjusted)