My reading of this thread's first several messages got me confused

The original message said 'Masterwork' and then the discussion faded into a discussion of 'epic'; AFAIK, epic is a category of story telling (examples,
Illiad,
Kalevala, LotR, WoT (maybe?),
Dune, Norse sagas, etc.). For more than a few years SF focused very much of gadget stories, and after you tell the story about the gadget you're done.
Regarding Masterworks, well, IMO SF can bring a few more things to the table than those mentioned.
Gateway by Fred Pohl is brilliant fiction very worthy of masterwork designation.
Fifth Head of Cerebus by Gene Wolfe and
The Moon is a Harsh Mistress by Robert Heinlein are both masterworks (brilliant fiction that stands up any piece of mmetic fiction you'd care to compare them to). YMMV