9. Why would you feel guilty about that? Everyone has their own preferences. I love all of Kazuya Minekura's work, however, Wild Adapter is considerably more 'mature' in plot and art style because she changed so much from writing Saiyuki. (Seriously, compare volume 1 of Saiyuki to Wild Adpter or even Saiyuki RELOAD.) Thusly so, people who delve in her manga tend to be pulled towards Wild Adapter more. From what I see, anyways. It seems to me that people who love Saiyuki more than anything else she's done have seen the anime first or have never read any of her other work at all.
Anyways, the rest of Kazuya Minekura's work is definitely under appreciated. Especially Bus Gamer. NEEDS MOAR BUS GAMER.