I've never broken a Presta valve. I've bent several, but never broken. They still work bent.
Presta is a one way valve when you are adding air. Schraders lose air when you attach and detach the pump. Plus, Prestas can be set up for tubeless where you can remove the valve stem easily and add Stans or similar sealant when it starts to dry up. Prevents you from having to break the bead to add the sealant.