This is education, not advice
The information here is written for the general reader and does not replace a personal medical consultation. It cannot tell you whether either operation is appropriate for your chin, your health or your circumstances.
No outcome is guaranteed
No treatment can be guaranteed. Numbness of the lower lip and chin can follow either operation and can be lasting; a device can move or become infected and may need to be removed; a bone segment can heal in a way that needs further surgery; and the settled result is judged months later rather than in the first weeks.
Neither operation corrects a bite
A genioplasty moves the chin segment rather than the whole jaw. A bite that does not meet correctly, a small lower jaw and an airway problem are assessed and treated as jaw concerns, and neither operation in this comparison reaches them.
Neither operation reduces a chin
Both operations add projection. A chin that is too prominent for the rest of the profile is a different problem, and adding to it would make the complaint worse.