The best replacement for midi is usb.

The best alternatives to midi are rated as following:
★★★★★  usb
★★★  audio
★★★  wav
★★  osc
★★  usb keyboard
★★  synth
★  keyboard
★  digital audio
★  mini lathe
★  full tower
★  digital piano
★  xlr
  cv
  timecode
  din
  cdj
  cdg
  anl
  polyphonic
  general midi
  maxi
  mid
  audio recording
  synthesizer
  mod
  midi

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

Other search terms related to midi and their ratings are:
★★★★★ keyboard
★★★ audacity
★★★ garageband
★★ ableton
★★ ipad garageband
★ sound card
★ you air supply
★ apogee duet
★ reason
★ fl studio
★ you harry nilsson
★ autotune
logic
mbox
logic pro
You have in mind a companion for midi and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of midi in all years. Click on graph for more.
midi
usb
audio