Buccal fat removal or jawline botox?

Thank you for your pictures.  I think the most important thing to understand here is what buccal fat pad removal does, and what it does cosmetically.  The buccal fat pad is in front of the masseter muscle, above the jaw bone and below the cheek bone (very crudely speaking).  By carefully removing it, you improve the highlight of the cheek bone and of the jaw line - in effect giving your face a more chiseled, contoured look.  In this manner it can improve the appearance of the jawline, but it is not actually affecting the underlying structures.  Botox to the masseter does exactly what you described - slight improvement to the lower face, but it is temporary.  Without a full exam and being able to see your entire face both at rest and in motion it is difficult to determine whether or not a buccal fat pad surgery is worth considering.  I hope some of this helps.  

Achieving a chiseled, less chubby face requires to address multiple factors in the face and the body composition to contribute to this physical finding. This analysis will help to determine what is the plastic surgery procedure(s) what could best help to correct a chubby face, thus achieve a slimmer more chilled face. 
Some of the physical findings that may need to be addressed to achieve a slimmer / chiseled face are: 
Lower anterior cheek fullness: this could be addressed surgically with buccal fat removal 
Lower posterior cheek fullness: this could be achieving my treating the masseter muscle ( a masticatory muscle) with Botox. The masseter muscle gives bulk to the lower posterior cheek fullness at the level of the angle of the jaw bone. Note: In order for Botox treatment of the masseter to work, at least 3 treatments of 25 units each side, 4 months apart should be done in order to "shrink" ( atrophy) the masseter muscle.
Overall body fat: weight loss to achieve a normal or low normal weight for the height ( normal BMI) is a must. (most models with chiseled face have  are "skinny" and therefore have a BMI in the low normal range) 
Anterior and lateral cheek bone projection: lack of cheek bone projection won't allow to have a chiseled appearance, event if the above factors are achieved. Therefore, it someone has not good cheek bone projection, he or she may require cheek augmentation/ enhancement with either soft tissue fillers like Voluma or cheek implants 

Patients interested in determining if buccal fat  removal may help to achieve a chiseled face should make a consultation with a Board Certified Plastic Surgeon specialized in plastic surgery procedures of the face.