The best replacement for ios is android.

The best alternatives to ios are rated as following:
★★★★★  android
★★★  android development
★★  android market share
★★  windows
★  osx
★  android security
★  mykonos
★  windows phone
★  android which is better
★  android apps
★  android comparison
★  android tablet
★  windows phone 7
★  honeycomb
★  naxos
★  droid
★  android first
★  paros
  kitkat
  catos
  android for gaming
  android 2.3
  ios xe
  os
  android 2012
  android operating systems
  boot2
  android sales
  webos
  android gaming
  android tablets
  android app revenue
  santorini
  ios xr
  junos
  ics
  ice cream sandwich
  os x
  android usage

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

Other search terms related to ios and their ratings are:
★★★★★ phonegap
★★★ xcode
★★★ objective c
You have in mind a companion for ios and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of ios in all years. Click on graph for more.
ios
android
android development