For me, Wunderlist is well done in offline access, super fast sync and a battery-friendly Mac app. I sometimes work in some place that does not allow internet connection, e.g. warehouse where phone signal is screwed, or some meeting rooms just block the signal due to their privacy.
In many years I still cannot find an alternative. May be Evernote(?)
Edit: Attach an image to explain why: https://twitter.com/Edditoria/status/1043481201443368960