The best replacement for android os is iphone os.

The best alternatives to android os are rated as following:
★★★★★  iphone os
★★★★★  android system
★★★★  apple os
★★★  windows mobile
★★  blackberry os
★  windows os
★  symbian os
★  apple ios
★  symbian

Your alternative for android os is not listed? Suggest!
Speaking about android os, one probably shouldn't forget about camera.

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



Google Trends

Scale is based on the average worldwide traffic of android os in all years. Click on graph for more.
android os
iphone os
android system