OK - here goes dipping my toe into a race in which I have no horse
(namely a penis, nor a child with one!).
I voted opposed despite the strong wording because of this ritual's link with patriarchal religion. First, I tend to lump circumcision in with old Judeo-Christian prohibitions against eating pork and shellfish. I've always thought that these things were thought necessary in ancient times for health reasons but that modern societies know enough about sanitation, refrigeration, cleanliness, etc... that it should be a non-issue.
Then, there's the association with female 'circumcision' which to my mind is entirely indefensible.
The only thing I know - albeit one data point doesn't make a trend - is that when an adult male has the procedure because it is medically necessary, it is
extremely painful and involves a much more extensive recovery period. Imagine having the surgery, then having erections (not like guys can control that!), stitches breaking loose, pain, more pain...A really bad 2-3 weeks to go through, believe me, and I was just there for moral support!