recommend HRM

I have always used the Polar F4 watch and chest strap for all of my HRM information, calories burned, target HR, etc. My chest band stopped working so I went online to order a new one- I couldn't believe all the different "bluetooth" gadgets that connect to iphones, sync with this site, etc. I ended up not ordering because now I don't know what is the best way to go. Any ideas for me? I am looking to track my HR, target HR, calories burned, and duration of exercise (not an all day count). Should I just order a chest strap and keep with my Polar? Or get one that talks to my iphone?