Ultherapy Vs Thermitight. Dollar for dollar which is more effective for skin tightening?

This is an easy answer. I offer both treatments and can tell you that dollar for dollar ThermiTight is a better treatment than Ultherapy. But, with both treatments choosing the appropriate candidates and the experience of the provider is critical. Make sure you see an experienced provider for an in-person consultation and evaluation. Best wishes.

Ultherapy is applied to the surface of the skin. The ultrasound waves reach into the superficial facial plane and second skin layer to stimulate new collagen. ThermiTight is a minimally invasive technique in which a probe is actually inserted deeply into the dermis, which is then heated up with radiofrequency energy. This also shrinks the collagen and stimulates the production of new collagen. 
Which therapy is best for you is determined by the degree of your sagging, amount of fat, and the quality of your skin. We did a trial comparing both, solely to the neck, and one did not show to be superior to the other. But if you also need to tighten the lower face and brow I tend to recommend Ultherapy. Results with either can be quite long-lasting — sometimes up to 2 or 3 years. Consulting a board-certified dermatologist will help you decide which treatment to choose. The best value can only be provided by choosing the most appropriate therapy for your particular case.

I don't think its fair to compare the two different modalities since one is on the surface and the other one is invasive (minimally invasive). Just like these two modalities cannot be compared with face lift. If I have to look at the modalities to tighten and lift the sagging areas I would personalize to each client's needs. What I look at is degree of laxity, person's desire to pick non invasive vs invasive procedure, does the person want any down time at all?, does the person want others not to know what was done etc. As far as cost is concerned you will have to get consultation for each one of them to see what the cost is since every practice has different cost levels. Overall go for the treatment that suits you.