Movies/show or books?
For the visual medium I'd have to go GoT, LotR, Star Wars. (I'd probably rank the books the same but I've never read any Star Wars material.)
Game of Thrones has an advantage in depth for me due to the show having about 64 hours of runtime so far. I've watched every episode many times and don't get tired of it. ASoIaF has a lot more material and I wish GRRM would finish it. It's nice to see the characters develop over seasons and years that movies have to skip a lot of.
The original Star Wars trilogy holds a lot of nostalgia and luckily the new films have gone back to more of their style. I thought the prequel trilogy was 'okay' when I first watched, but once the story was known they've become unwatchable for me. Just awful.
I also really liked the LotR trilogy. They were a lot of fun despite some achingly slow portions and lots of walking. The Hobbit films weren't as good imo and like the SW prequel trilogy I don't care to watch them anymore.
