The best replacement for polar loop is fitbit.

The best alternatives to polar loop are rated as following:
★★★★★  fitbit
★★★★★  fitbit flex
★★★★  garmin vivofit
★★★★  nike fuel band
★★  jawbone up24
★★  fitbit force
★★  polar ft7
★★  jawbone
★★  basis
★  nike fuel
★  withings pulse
★  misfit shine
★  jawbone up
★  nike+ fuelband se
  vivofit
  bodymedia
  fuelband se
  jawbone up 24
  fitbit one

Your alternative for polar loop is not listed? Suggest!
Speaking about polar loop, one probably shouldn't forget about polar beat.

Other search terms related to polar loop and their ratings are:
★★★★★ polar beat
★★★ h7
You have in mind a companion for polar loop and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of polar loop in all years. Click on graph for more.
polar loop
fitbit
fitbit flex