The best replacement for opera is firefox.

The best alternatives to opera are rated as following:
★★★★★  firefox
★★★★  google chrome
★★★★  musical
★★★★  chrome
★★★  safari
★★  oratorio
★★  mozilla
★  operetta
★  opera mini
★  internet explorer
★  opera next
★  symphony
★  ie
★  light opera
★  firefox 3
★  ashton
★  dolphin
  chrome android
  fidelio
  ballet
  musical theater
  firefox browser
  musical theatre
  foxfire
  musicals
  stage musical
  italian opera
  uc browser
  chromium
  maxthon
  broadway musicals
  skyfire
  safari which is better
  bolt
  mozilla firefox
  netfront

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

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



Google Trends

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