We've done both the KTTK tour (2003) and the Hidden Treasures of World Showcase tour (2001). Our tour guide for KTTK was Rae, and I think that contributed to making the tour very special. When we took the Epcot tour, thing were much less organized, name tags written on label tags with Magic Marker, no pins, etc. I'm not sure this is still the case. I guess I'd say that the KTTK tour gave more bang for the buck, but you're talking about Backstage Magic, the $200 all four parks tour right? Each of the tours taught us interesting things, and let us see some backstage areas.
In April we're doing Backstage Safari at AK.