The best replacement for android 18 is vegeta.

The best alternatives to android 18 are rated as following:
★★★★★  vegeta
★★★★  cell
★★★  trunks
★★★  android 17
★★  frieza
★★  hercule
★★  zangya
★★  mighty mask
★  goten and trunks
★  cooler
★  meta cooler
★  android 19
★  bio broly
  krillin

Your alternative for android 18 is not listed? Suggest!
Speaking about android 18, one probably shouldn't forget about krillin.

Other search terms related to android 18 and their ratings are:
★★★★★ krillin
★★★★ bulma
★★★ videl
You have in mind a companion for android 18 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of android 18 in all years. Click on graph for more.
android 18
vegeta
cell