I just went through this decision, and my biased but informed opinion is that there is no medical reason at all to circumcise. The smaller chance of HIV is so incredibly slight that you can't really count it as a benefit; it's more of an excuse. I know it sounds harsh and dramatic, but when you look at circumcision for what it is - cutting off a sexually sensitive part of a baby boy - without all the cultural baggage, it sounds silly at best and cruel at worst. I mean, would you do it to a daughter?
That said, in my informal poll of adult men, every one of them was happy with their penis, cut or un-cut. It's important to remember that if your son decides on his own that he wants to be circumcised, he can have the procedure done later. But you can't undo it once it's done. If you're concerned about cleanliness, well, do you really plan on being such a lazy parent that your son doesn't learn how to clean himself? Of course not. Give yourself some credit.
For what it's worth, I'm Jewish. This opinion was formed after a lot of research and soul searching.