I think female circumcision is disgusting, but I will confess an ignorance to any medical advantages that could be yielded from it. I think similarly, regarding male circumcision, when it's performed as a religious ritual. For instance, in Judaism, it's performed with the express purpose of dulling the pleasure of sex for the male. Regarding any medical benefits male circumcision would bring, I think that not only answers itself, but is separate from my main objection to it.
I think the whole religious reasoning behind the genital mutilation would be laughable if it didn't have such a negative affect on the people it's done to.
"God created us in his own image, he is infinitely knowing and his design perfect. Just pass me that sharp stone so I can saw the end off of this penis and shave off that clitoris." It's not only disgusting, and immeasurably harmful, it's absolutely nonsensical as far as religious idea of design can go.