The best replacement for google play is itunes.

The best alternatives to google play are rated as following:
★★★★★  itunes
★★★★  spotify
★★★★  app store
★★★★  amazon
★★★  itunes match
★★  android market
★★  rhapsody
★★  apple store
★  play store
★  amazon mp3
★  beats music
★  amazon prime
★  vudu
★  amazon app store
★  spotify premium
  samsung apps
  itunes store
  amazon cloud
  apple app store
  kindle books
  windows store

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

Other search terms related to google play and their ratings are:

★★★★★ android
★★★★★ google wallet
★★★★★ sonos
★★★★ kindle fire hdx
★★★★ kindle fire
★★★ cyanogenmod
★★★ gapps
★★ trio tablet
★★ nook
★★ rooting kindle fire
You have in mind a companion for google play and it is not yet here? Propose!

Google Trends

Scale is based on the average worldwide traffic of google play in all years. Click on graph for more.
google play