Everything in ANH and ESB was memorable, including a good deal of ROTJ.
That is one of the problems with the prequels, there wasn't any moments that sucked me in.
ANH and ESB were such great pieces of art, and each scene can be enjoyed on their own. Even people who haven't seen them before know some of the imagery, because it stays with you. You have to have seen the prequels a few times to remember much about them.
Star Wars used to be a thing that everybody knew about and it was instilled in our culture. Star Wars wasn't a movie, it was an experience.
Even ROTJ had those moments of awe that you could take with you and tell your friends about it.