I chose Tymlos because the pen has 8 clicks and so dose is adjustable. I am sensitive to meds and needed to titrate up, and am still at only 6-7 clicks, which my doc says is okay. I also had breast cancer. Evenity seems to have fewer side effects but is so new I wanted to wait on that. Tymlos side effects change mostly for the better after a month or so and might include headache, nausea, heart palpitations, but if you start at 2-4 clicks you can avoid them if you are one of those who have side effects.