Genioplasty vs. Mandibular Advancement
It is true that a sliding genioplasty will improve your facial profile and look. However with a significant Class II malocclusion it would be better than you have a BSSO which would be a better long-term functional approach. But if you decide not to opt for a mandibular advancement, a sliding genioplasty would provide a nice improvement.
Genioplasty versus chin implant
A Genioplasty is performed by an oral surgeon and involves making cuts in the mandible and setting it forward. The procedure is performed in the hospital as an inpatient procedure. A chin implant involves inserting a Silastic implant through a sub mental approach under local anesthesia as an outpatient procedure. Chin implants are manufactured in a variety of sizes and shapes which is best determined at the time of the consultation. For many examples of chin implants, please see the link below
Chin surgery can improve the face. However, if you have for instance a gummy smile, your upper jaw should be re-positioned, rater than having chin surgery done.