What’s better in my case; a sliding genioplasty or chin implant? (Photo)

 Hi, I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  From the photos, your chin is very weak.  When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  
 Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut segments of bone).  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.    Which is better, chin implant or sliding genioplasty?  We place silastic chin implants through a small, curved incision under the chin using local anesthetic in 30 minutes or less.  This is "far" less invasive than a sliding genioplasty that requires cuts in the bone with plates or screws.  For that reason and because the aesthetic results are so good with a properly placed silastic chin implant of the correct shape and size...in my humble opinion there's no comparison.  The chin implant is quicker, easier, with far less surgery and healing, less unwanted side effects with results that are highly effective and reliable.
Hope this helps.

You have a vertical facial growth pattern so that the lower jaw is quite 'narrow' as well. The inability to naturally close your lips requires the 'mentalis/chin muscle' to strain; and compress the chin area. An implant is much less ideal in your case since the muscle will 'force' the implant 'into' the underlying bone - not a positive idea. A genioplasty is preferred. However, one cannot move it too far forward or the face will look 'longer'. Talk to a maxillofacial surgeon in your area.