The best replacement for 8.1 is 6.0.

The best alternatives to 8.1 are rated as following:
★★★★★  6.0
★★★★★  8.1 pro
★★★★★  8
★★★★  7
★★★★  windows 7
★★★  duramax
★★  8.0
★★  7.4
★★  windows 8
★★  6.6
★★  v10
★  454
★  6.8
★  mavericks
★  rt 8.1
★  8 performance
★  rt
★  windows 8.1 pro
  mac
  win 7
  voodoo hoodoo
  linux
  windows 8 pro
  windows 8.0
  8.1 n
  8.2
  ubuntu
  windows rt
  ford v10
  windows rt 8.1
  window 8
  7 performance

Your alternative for 8.1 is not listed? Suggest!
Speaking about 8.1, one probably shouldn't forget about allison transmission.

Other search terms related to 8.1 and their ratings are:
★★★★★ allison transmission
★★★★ classic shell
★★ windows 8 key
★★ allison trans
★ start button
★ start menu
★ login
skydrive
You have in mind a companion for 8.1 and it is not yet here? Propose!



Google Trends

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8.1
6.0
8.1 pro