The best replacement for fitbit is jawbone.

The best alternatives to fitbit are rated as following:
★★★★★  jawbone
★★★★★  bodybugg
★★★★  bodymedia
★★★  polar
★★★  nike fuel
★★★  nike fuelband
★★  basis
★★  fuelband
★★  up24
★★  garmin
★★  nike
★★  withings
★★  vivofit
★  nike fuel band
★  jawbone up
★  polar loop
★  heart rate monitor
★  up
★  polar watch
★  jawbone up24
★  up band
★  pedometer
★  pebble
★  activelink
★  fitbug
★  bodymedia fit
  withings scale
  myfitnesspal
  striiv
  up 24
  hrm
  polar ft4
  loop
  nike+
  garmin vivofit
  nike band
  shine
  active link
  up bracelet
  zeo
  pulse
  fitbit ultra
  up jawbone
  gowear fit
  directlife
  omron
  fuel

Your alternative for fitbit is not listed? Suggest!
Speaking about fitbit, one probably shouldn't forget about weight watchers.

Other search terms related to fitbit and their ratings are:
★★★★★ weight watchers
★★★★★ myfitnesspal
★★★ runkeeper
★★★ lose it
★★ heart monitor
★★ hrm
★ my fitness pal
★ heart rate monitor
★ friends
tory burch
You have in mind a companion for fitbit and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of fitbit in all years. Click on graph for more.
fitbit
jawbone
bodybugg