The best replacement for withings is fitbit.

The best alternatives to withings are rated as following:
★★★★★  fitbit
★★★  ihealth
★★  fitbit scale
★★  ihealth scale
★★  ihealth blood pressure monitor
★★  aria
★  baby monitor
★  wifi baby
★  tanita
★  ihealth blood pressure
  fitbit aria
  omron
  aria scale
  dropcam

Your alternative for withings is not listed? Suggest!
Speaking about withings, one probably shouldn't forget about runkeeper.

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



Google Trends

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