The best replacement for intellij is eclipse.

The best alternatives to intellij are rated as following:
★★★★★  eclipse
★★★  netbeans
★★★  eclipse android
★★★  webstorm
★★★  android studio
★★  pycharm
★★  phpstorm
★★  rubymine
★  sts
★  eclipse scala
  flash builder
  myeclipse
  jbuilder

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

Other search terms related to intellij and their ratings are:
★★★★★ maven
★★★★ github
★★★★ gradle
★★★ tomcat
★★★ bitbucket
★★★ jetty
★★ android sdk
★★ libgdx
★★ scala
★ flex
grails
You have in mind a companion for intellij and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of intellij in all years. Click on graph for more.
intellij
eclipse
netbeans