Circumcision generally leads to reduced glans (head) sensitivity, but the difference is not as big as people make out to be, but its definitely there, especially when cumming e.g. more likely to experience too intense of an orgasm and can't move ya dick. More so if the guy never masturbated much, the first few times he will be sensitive as fuck. The foreskin always covers your glans which prevents it from being exposed (contact with clothes etc), more moist..etc
The downside with being uncut is you need to make sure to clean it properly, I know WLs who are not a big fan of BBBJ an uncut penis, I mean there's nothing wrong with it if you keep it clean and have good hyenine, but some guys don't lol, also the foreskin can become problematic for some guys if can't retract it properly causing problems for sex.