The best replacement for superuser is busybox.

The best alternatives to superuser are rated as following:
★★★★★  busybox
★★★★  serverfault
★★★  stackoverflow
★★★  supersu android
★★★  supersu
★★  superuser elite
★  superuser
  super su

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

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



Google Trends

Scale is based on the average worldwide traffic of superuser in all years. Click on graph for more.
superuser
busybox
serverfault