I'm always a bit shocked when I see people express this. I work in a office with roughly 100 macs and 100 windows. The macs are FAR more stable and less buggy. I've had this experience three different times at various companies. Yet online I see people saying that OS X is just as buggy but they never point what part is.
Well, for example, with the most recent updates I had problems with wifi stability and thunderbolt peripherals not working properly. They've been fixed now, but it's still kind of surprising they creep up given the limited amount of hardware the OS has to target.
Are the macs running the latest version of OSX? From what I've read and experienced, OSX declined in quality when Apple stopped charging for OSX and started using it to drive hardware upgrades. These days OSX works fine if you have the latest, greatest, most expensive Mac hardware but if you try to upgrade an existing machine, that's when you get errors.