I go back and forth on this... I liked having my son end of February - until I realized at his first birthday that all his birthdays from hereon out, the likelihood of his friends cancelling on his party is high because of flu-season and that makes me sad!
I am a September baby but that is the school cut off date and even though it's a lovely month, I remember hating it as a kid.
So for that reason I think May-July is the best month to have a birthday.
How about you?