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

In your case I think you could go either way. Both have their advantages. Generally speaking, the implant surgery is a bit easier to recover from and carries less risk of nerve injury. However, the amount of projection can be limited.  If you want very significant change (or are averse to implants) then a bony advancement may be a better option for you, especially if you want to add vertical height.  My recommendation would be to meet with a surgeon who performs both of these procedures so you can get a realistic and unbiased opinion on which would be best based on your goals. Good luck!

In cases that require a significant horizontal advancement, I prefer a sliding genioplasty. We perform this surgery in the office with intravenous sedation and I can advance the chin up to 9 mm. You would benefit from as much advancement as possible.In addition, it will relax the mentalis strain that is seen in your photo.

Either one is ok! You just have to read about them and seee what fits you and your needs. Talk to different doctors. 

 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.