The best replacement for omnifocus is things.

The best alternatives to omnifocus are rated as following:
★★★★★  things
★★★★  evernote
★★★  pagico
★★  2do
★★  todoist
★★  omnioutliner
★★  omniplan
★  things 2
★  pocket informant
★  wunderlist
★  toodledo
★  asana
★  things ipad
★  trello
★  reminders
★  omnifocus 2
★  remember the milk
★  things for ipad
  todo
  any.do
  daylite
  org-mode
  doit.im
  nozbe
  gneo
  firetask
  onenote
  clear
  bento
  devonthink
  things review

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

Other search terms related to omnifocus and their ratings are:
★★★★★ evernote
★★★★ siri
★★★★ omniplan
★★ basecamp
You have in mind a companion for omnifocus and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of omnifocus in all years. Click on graph for more.
omnifocus
things
evernote