My butt needs serious help, which would be my best option: Emsculpt, CoolSculpting, or a BBL? (Photos)

Typically a combination of sculpting the waistline with liposuction and augmenting the buttock with implants +/- the hips with implants provides the best chance for a long lasting and desirable "hour-glass" figure. However, please keep in mind that a physical exam is always first necessary before providing any final surgical recommendations. Based upon your photos, a Stanton Anatomic shape buttock implant may serve you best.  Please read on:There are currently only two acceptable surgical options for augmenting and enhancing the buttock/hip area: 1) Brazilian Butt Lift (aka BBL) - utilizing the patients own fat from liposuction then transferring it into the buttock and/or hips and 2) Buttock and cosmetic Hip Implants (soft silicone rubber implants that cannot rupture &/or leak). Both are options but what it comes down to, like any surgery, is proper patient selection and long-term results. Implants provide the only guarantee of sustained permanent results and tend to be ideal for plumping/perking up deflated buttocks. Fat typically melts away leaving disappointing results after 12 months.  BBL is also known to be the most deadly procedure of any cosmetic  surgery with an estimated death rate of ~1:3000 to 1:10,000.  Emsculpt and Sculptra will provide literally provide only puny results to the buttock and thus are huge waste of hard earned money.   

id suggest surgery / liposuction / body contouring to get you a new shape and size and then maintain with TRUSCULPT FLEX, sculptra, and RF treatments like venus legacy or forma.  
You need a formal evaluation by an expert in body shaping and contouring to determine what is best.  Traditional liposuction awake and smart liposuction are old methods and do very poorly for tightening skin or significant skin tightening or contouring.  Small problem areas can be improved slightly by these methods.  The best in body contouring not only removes fat with energy devices like VASER ultrasound but also internally heat the skin with radio-frequency devices such as J PLASMA/RENUVION, InMode BodyTite, ThermiRF to heat the under surface of the skin and tighten it at the same time as fat removal. These combinations are called 4D HIDEF VASER contouring and can only be done by a well . trained body contouring specialist. At the same time fat should be harvested, PRP and stem cells added and injected into muscles or indentations/cellulite to get body shaping and contouring.  This is known as a Brazilian butt lift when you inject the fat to the buttock for contouring and lifting, but fat can also be used in areas such as the chest/breast, arms/shoulders, calves and face.  Cellulite should also be treated with cellfina, sculptra, subcision and/or fillers such as bellafill, renuva synthetic fat, or sculptra.  If skin is very loose before surgery then it will need to be removed such as lower abdominal skin (tummy tuck/abdominoplasty), breast skin (breast lift), arm skin (brachioplasty).  Overall you need a full assessment, but simple liposuction alone will not tighten skin and needs a combination of various methods -- fat removal, skin tightening, defining, fat grafting, skin removal -- to get the best in body contouring and body sculpting.  Dr. Emer.

I suggest doing the BBL , none of those noninvasive treatments are going to match the results of a BBL and you will spend less money with a BBL than with doing all those noninvasive ones