For most people, the anterior approach is more appealing cosmetically. The incision can be done along a natural crease in the neck. After it heals, there is minimal (if any) scar showing.
You should discuss this concern with your surgeon. There may be other important reasons to choose one method of surgery over another. Decompression and fusion can be done from the back of the neck using a posterior approach.
The level of the spine being operated on can make a difference. Any previous surgeries in the area (including any cosmetic procedures) may make a difference. If you want to avoid possible complications, a trial of at least six months of conservative care is advised. This can include medications, physical therapy, and possibly steroid injections.