What is the best skin tightening treatment?

Though there are many options and you need to go in and be evaluated, besides all of that..my go to is the TruSculpt 3D these days for the arm skin tightening! It is amazing for this! 
This technology was just released in May of this year but it is taking the Cellulite reduction and tightening to a whole new level of greatness! I am soo soo impressed.
My recommendation is look on Cutera.com website for a provider of TruSculpt 3D near you and go there first for an evaluation because if you fit everything to have this done...this will do the trick most likely in a single session,too! And if you go to a clinic or office without this technology then I don't think it will be what is recommended first line since it isn't even there! 
Hope this helps and best of luck with your results...I know you will be pleased with TruSculpt 3D..given results we have seen..it is a Wow! 
Dr. Amy 

It is hard to say what one treatment is "best" for skin tightening.  In general, anything that does a good job of heating the dermal layer and the muscle layer should result in significant tightening.  Some very good options are Ulthera and Vaser Shape.  A newer treatment, J Plasma, is also showing excellent tightening.  I would recommend a consultation with a physician who specializes in aesthetic medicine.  If you have excess fat in addition to loose skin, you may be a candidate for Vaser Liposuction.  However, if your skin is extremely loose, you may need to consider surgically removing some of it. Best of luck to you.