which is better a neurosurgeon or an orthourgeon?

More money comes with more responsibility and stress. So keeping this factor, Orthosurgeon may have less stress compared to a Neurosurgeon, who earns much more than an Orthosurgeon.
Here, the question is not just about salary and stress, let it move towards service to the mankind, responsibility and accountability towards a patient. Both of these surgeons have more or less relatively equal service to the mankind but the Neurosurgeon's part has more challenges.
Above all, it is not only the specialisation but it also depends upon the choosers what they choose, what interests them, where they can dedicate themselves...