The best replacement for 2do is things.

The best alternatives to 2do are rated as following:
★★★★★  things
★★★★★  omnifocus
★★★★  todo
★★★  toodledo
★★  awesome note
★★  wunderlist
★★  todoist
★★  pocket informant
★★  reminders
★  todo appigo
★  remember the milk

Your alternative for 2do is not listed? Suggest!
Speaking about 2do, one probably shouldn't forget about gtd.

Other search terms related to 2do and their ratings are:
★★★★★ gtd
You have in mind a companion for 2do and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of 2do in all years. Click on graph for more.
2do
things
omnifocus