The best replacement for protools is cubase.

The best alternatives to protools are rated as following:
★★★★★  cubase
★★★★★  nuendo
★★★★  logic
★★★★  sonar
★★★  cakewalk
★★  reason
★  garageband
★  digital performer
★  adobe audition
★  audition
  ableton
  reaper
  studio one
  logic 8
  logic pro

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

Other search terms related to protools and their ratings are:
★★★★★ mbox
★★ motu
★ reason
★ an mbox
garageband
axiom
cubase
You have in mind a companion for protools and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of protools in all years. Click on graph for more.
protools
cubase
nuendo