Things works extremely well for me.
I use this app each day on my iPhone, iPad and two Macs.
No problems with swiftly and accurately cloud syncing all four devices. The app has excellent organizational options. It can be used for the simplest reminders, as well as for developing, tracking and achieving complicated projects.
Things fulfills all my requirements for an app of this genre.
Gord P. about Things, v2.8.6