Fun to look at but this is an impossible list to agree on. Here was the writers methodology:

Our methodology was simple: we selected the highest-earning title from each “summer,” a colloquial releasing window stretching from the beginning of May to Labor Day, with noteworthy dispensations for Marvel’s attempts to move the goalposts back to the last weekend in April via the unignorable Avengers: Infinity War and Endgame. In order to prevent an unfair advantage for May drops over those in August, we also chose to consider a film’s total grosses rather than everything raked in during the summer months. (In this respect, 1994 presented an odd judgment call: Forrest Gump had outdone The Lion King by that December’s end, but re-releases over the years have now boosted Simba and the gang over Alabama’s favorite son. We figured that doesn’t really count, and went with Gump.)