The best replacement for garageband is logic.

The best alternatives to garageband are rated as following:
★★★★★  logic
★★★  logic express
★★★  audacity
★★★  pro tools
★★  fruity loops
★  fl studio
★  mixcraft
★  logic pro
★  ableton
★  protools
★  audition
★  ableton live
★  music studio
★  cubase
★  acid
★  cubasis
★  nanostudio
★  logic pro x
  logic x
  rocksmith
  studio one
  soundtrack
  band in a box
  reaper
  lmms
  logic studio
  cakewalk
  magix music maker
  amplitube
  session
  audacity mac

Your alternative for garageband is not listed? Suggest!
Speaking about garageband, one probably shouldn't forget about midi keyboard.

Other search terms related to garageband and their ratings are:
★★★★★ midi keyboard
★★★ irig
★★★ rocksmith cable
★★★ mbox
★★ audiobus
★ mbox 2
★ reason
★ yamaha keyboard
★ audio interface
★ protools
★ idrum
★ synthstation
★ maschine
midi
imovie
recording
real instruments
digi 002
You have in mind a companion for garageband and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of garageband in all years. Click on graph for more.
garageband
logic
logic express