Joan of Arc is certainly problematic. While I agree that it deserves
somewhat more scholarly attention than it's received, I don't think it will
show up on anyone's ten best list anytime soon.
Except Twain's. Which brings me to the question you've raised: just why
Twain think this his best book?
I've always thought the answer could be found deep in Twain's psyche. While
he gained popularity & fortune from the general public, he wrote little that
appealed to the tender sensibilities of his wife Livy and (perhaps even more
importantly) his beloved daughter Susy. Some argue, of course, that Livy
bowdlerized some of Twain's writings to bring them more in line, and all
that; but that's not what I'm talking about.
I'm not sure Twain himself ever really respected much of his own work.
Somewhere deep inside I think he wanted to be Howells-- the eminently
respected and liked man of letters-- just as another part of him wanted to
Andrew Carnegie or H.H. Rogers. Although we modern literary critics spend a
good deal of time defending Twain from the accusations of being a "mere"
humorist, I think Twain often felt himself so, to his great pain. _Joan of
Arc_ seemed to Twain the kind of book to merit respect from Livy, Susy,
Howells, and himself.
I also seem to remember Twain describing Joan as Susy, or vice versa. One
can see how the linkage would endear the book in Twain's mind.
University at Buffalo