Best Filler for "Butt Chin" Dimple?

Without a doubt, I believe that the best filler for chins is Radiesse. Being that it is made of calcium hydroxyapatite (the same substance in bone and teeth), it looks and feels incredibly natural. Other fillers risk being more moldable, as well as lumpy or mobile. 

Most commonly used facial fillers are HA (Hyaluronic acid) based fillers, like Juvederm, Restylane, Perlane, etc and Radiesse (calcium hydroxylapatite). These are temporary fillers, with duration of about 12 months or so.  Both types are equally effective and can be used pretty much everywhere in the face (except Radiesse is not indicated for lip augmentation).  I suggest you start with one of these first, and then you may consider other options such as either a permanent filler or implants.

Without seeing pictures it is impossible to say for sure. But generally the use of fat injections for tear troughs and other facial areas is the most cost-effective way of facial soft tissue augmentation over the long-term.