The best replacement for bash is sh.

The best alternatives to bash are rated as following:
★★★★★  sh
★★★★★  zsh
★★★★★  csh
★★★★  ksh
★★★★  tcsh
★★★★  python
★★★  francis
★★  dash
★★  if
★★  perl
★★  powershell
★  test
★  batch
★  terminal
★  korn
★  bourne
★  frenzy
  exit
  if statement
  cleave
  fish
  team francis
  francis reign
  icons
  shell
  smash
  &&
  cmd
  conditional
  frankie j
  flameslinger
  korn shell
  dos
  bash2
  class d
  bsh

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

Other search terms related to bash and their ratings are:
★★★★★ expect
★★ variables
★ ssh
★ alias
You have in mind a companion for bash and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of bash in all years. Click on graph for more.
bash
sh
zsh