Arthur Hlavaty did a recent blog post on John Barth, a favorite writer of Arthur's and also a favorite writer of Robert Anton Wilson.
"I fear that John Barth is a literary Nehru jacket: once the darling of Academe, now just another cis het white male. His work could profit from the kind of extensive and intensive study Brian Boyd gave Vladimir Nabokov, but I fear that will not happen," Arthur writes, before going on to talk about his favorite among Barth's tales, Tidewater Tales.
As for RAW, see this letter to Robert Shea's No Governor fanzine; Wilson's favorite Barth novel was Sabbatical, but he liked Barth's other books, too:
Sometimes I find it astounding that we have lived under fascism for 40 years while continuing the rituals of democracy -- and that hardly any "major" novelist has tried to grapple with this issue. I salute Barth for his subtlety and the eerie atmosphere he creates in describing our increasingly Machiavellian world. To be brutally frank and eschew false modesty, I think only Mailer, Pynchon and myself have captured the terror of the situation as well as Barth did in that book.
Oh, yeah, I like Barth's other books, too. Sabbatical just happens to be my favorite.