Sacrosanct
Legend
Otherwise, Conan HYBORIA
Are Howard's works public domain? Date wise, they should be, but I seem to recall where for some reason, someone holds the IP rights to them. Although, I'm not quite sure how that works.
Otherwise, Conan HYBORIA
Erickson's (and Esselmont's) world from Malazon Book of the Fallen series. I think that the Warren magic would be hard to replicate in 5E though.
Also Cook's Black Company world and Martin's Game of Thrones world both of which should be relatively easy to bring to 5E. I also want Dragonlance.
Also Bakker's Second Apocalypse Series world would be cool as well.
It would be a bit tricky because it's not a really good match for 5e, but I would love love love to see the world of "Sunless Sea" made into an RPG....