My boys are each others' best friends. They play together and watch out for each other. DS3 is finally getting to the age to really start keeping up with his brothers.
Boys are easy to care for - you wash them and dress them - no worries about taking care of long hair or doing hairstyles (despite that this is one thing I'm looking forward to doing with a girl, but it does make getting ready go pretty quick).
They're all into the same toys, so it's easy to keep one playroom for them all to share.
As other moms of boys have said, I really am the super mom in the house. It's so sweet to hear the random "Mommy, you're so pretty" or "You look like Princess Leia today!" It just brightens your day :) They talk about someday finding a girl to marry who's just like me!
They have a great imagination and can play with anything from cardboard boxes to sticks and string.