If my friend said that, my voice would rise in anger as I state all of my logical reasons so that she/he will be proven scientifically imprecise.
If it was my enemy who said that... I'd probably throw her/his reasons back at their faces and hit the target. But if it was my arch-enemy on the other hand...I'd probably jump up, lose all self-control, screaming about him not deserving my ex-teacher.
i think i would tell them that there our pros and cons to each person and neither of them is better than the other and they shouldnt say that one is better than the other. That would be my reaction to a friend. To an enemy would be: walk away before i said some AWFUL things because NO ONE should diss Johnny especially an enemy
If it was my friend, I would sigh and tell them to be quiet and find some small way to get my revenge on them.
If it was my enemy, I would say, "The only thing worse then your jokes are your teeth!" And find some bigger way to get my revenge.