I loved Brooks as a teenager, and although SoS's main plot line was a rip-off, my fellow Wurtsian Horseman Grimward pointed out quite properly that there was a lot in SoS that was dramatically different from LOTR. In the seventies, there were a lot of Tolkien ripoffs. The other big one that comes to mind is Dennis McKiernan's Iron Tower series, which is so close to LOTR it is sickening. He, like Brooks, got much better.
Shannara was much more american (note the small "a") than LOTR, which was, of course, quintessentially British.
Elfstones, to me, was the height of Shannara. Though all the stories were compelling, to an extent, their formulaic nature tired me, and I gave up at FKoS. But Elfstones, that was special. The ending floored me, and even now when I think of my first read, I'll never forget that feeling. Elfstones ended with so much sacrifice, that it made the story come alive. The sacrifice of the characters really made the book special.
Given the above comments (I trust Gollum and Grimward implicitly), I will have to try The Word/Void books.