I think Shannara is a lot better than its rep. Yes, the first book was terribly derivative. But Terry already started deconstructing a lot of the tropes in Elf-Stones. I don't remember much about Wish-Song, I felt it was pretty boring, but the four book series after that was pretty great und really made a lot out of the fantasy post-apocalypse setting. I never got beyond that, and more recently, I tried to start were I'd left off about 30 years ago and just couldn't get into the writing anymore ... but I'd wager that all in all, it would make a much better RPG setting than novel series.