There were definitely other Vietnam War and related films like Platoon and Coming Home which were probably more highly regarded at the time but haven't had the staying power of Apocalypse Now.

I recall apocalypse now being extremely popular at the time of its release. Maybe that was just my social circle?

It was moderately successful at the box office ($100m worldwide) after a very troubled production but it only won sound and cinematography Oscars. Whereas Platoon for example won Picture, Director, Editing, and Sound. Coming Home won Best Actor and Actress.

Apocalypse Now wasn't a flop and had a reasonably good critical reception at the time (although Brando's performance was criticized) but overall it was seen as pretty middle of the road among Vietnam War and Vietnam War-adjacent (e.g. Born on the Fourth of July) films. Being seen as a great film by many mostly came after its initial release.