I have some after market ones I bought that broke, mostly car chargers, but I have never had the one that comes with the phone break. It seems like you would have to be pretty tough on them to break them.
I've tried both. The data cord that came with it is lost (but there are two others like it in the house, which usually work, but not at my computer). The car charger ones that I have gotten seem to not fit in tightly enough.