Is it advantageous to have a bone graft from yourself rather than a cadaver?

Sometimes: Major advantage is less chance of rejection but then the disadvantage is there may be a donor site involved.

Yes: Bonegraft from yourself is called autograft and is considered the 'gold standard' of bonegrafting in dentistry. That said, allograft (bone from cadaver) work well too in most instances.

Your self: Autogenous bone (your own bone) will have all the bmps (bone growth factor), the structure for scaffolding, the protein and tissue types and thus never get rejected. It is a gold standard of bone grafting. It is osteogenesis, osseoconductive, and osseoinductive. Allograft (from other human) is only osseoconductive. In simple grafting, allograft used because it eliminates a donor surgical site.

Less $ more compatib: Ones own bone is often less expensive and more compatible.