The best replacement for audacity is garageband.

The best alternatives to audacity are rated as following:
★★★★★  garageband
★★★  reaper
★★★  audition
★★★  goldwave
★★  ableton live
★★  sound forge
★★  cubase
★★  ardour
★★  pro tools
★★  adobe audition
★★  mixcraft
★  protools
★  ableton
★  fl studio
★  wavepad
★  soundbooth
★  kristal
★  cakewalk
★  wavosaur
★  garage band
★  vinylstudio
  glass cannon
  logic pro
  lmms
  wavelab
  elemental exposure
  acoustica
  wave pad
  traverso
  cool edit
  spin it again
  studio one
  magix
  cool edit pro
  krystal
  garageband better
  virtual dj

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

Other search terms related to audacity and their ratings are:
★★★★★ lame
★★★★ autotune
★★★ asio
★★ stereo mix
★ ffmpeg
★ lame mp3 encoder
★ gverb
★ soundflower
★ usb input
★ midi
★ karaoke effect
★ vst
usb microphone
asio4all
mbox
plugins
blue snowball
ion usb turntable
karaoke
lame encoder
reverb
gsnap
You have in mind a companion for audacity and it is not yet here? Propose!



Google Trends

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