Thank you for your question. I use both and many other technologies successfully in my practice. Without a full consultation it is difficult to say which of the many choices you would have, are best for you. However, in most cases I recommend more than one device or treatment to effectively target the area.
To remove excess fat and contour the arms, I might perform liposuction using the BodyTite device for example (this is just one of many liposuction devices I use). The radio frequency combined with the liposuction action will help to tighten the loose tissue. Post liposuction I would recommend that my patient undergo maintenance treatments with the Venus Freeze, TiteFx, SmoothShapes or one of my many other devices, to Enhance the tissue tightening effect of the surgery and to ensure the skin maintains it's contours. Devices like the Venus Freeze do not use cold technology as stated above, they use radio frequency which is warm. The heat is what causes controlled damage to the tissue allowing the body's natural healing response to occur Stimulating the fibroblasts to create more collagen and unravelling the elastic fibers. This makes your skin tighter and will address any laxity concerns you have.
The message here is to have an in person consultation with a cosmetic plastic surgeon and let them help you decide what treatment is best for you. It's not just the device that matters when choosing a procedure to address your concerns, it's the hands and head that perform the treatment or procedure that will make the difference.