The best replacement for organ is piano.

The best alternatives to organ are rated as following:
★★★★★  piano
★★★  tissue
★★  corti
★  keyboard
★  gland
★  muscle
★  electronic organ
  muscle spindle
  part
  hammond
  organism
  electric piano
  pipe organ

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

Other search terms related to organ and their ratings are:
★★★★★ body
★★★ moog
You have in mind a companion for organ and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of organ in all years. Click on graph for more.
organ
piano
tissue