"Epitaph" is one of their best songs, so no surprise you like it so much.
Someone already mentioned "Starless," but also check out "Matte Kudasai," "Frame By Frame," "The Night Watch," "In The Wake Of Poseidon" and then, finally, the epic "Lizard." King Crimson runs the gamut from soft and beautiful to some of the most chaotic, abrasive and heavy progressive rock imaginable. Give "21st Century Schizoid Man," "Larks Tongue In Aspic: Part II," "Thela Hun Ginjeet" and "Cat Food" a listen for examples of their latter sound.
Definitely at least listen to
In The Court Of The Crimson King. It's a landmark album and while it's not my favorite album by them, everyone should hear it at least once. The 40th Anniversary Edition is the best sounding version, but I don't know how readily available it still is. Might be a bit pricey to get a hold of, but it is worth it.