Taskwarrior is very nice, but I found org-mode combined with the mobile client orgzly even nicer. Export to ical, sync to server and you have it in your watch or mobile calendar as well.
Do you struggle with orgzly's sync management though? Things seem to get out of sync a lot with syncthing, so I've stopped editing lists on my phone (which... is starting to defeat the current iteration of the setup). Or do you use dropbox?
With WebDAV on MobileOrg, I never really had these problems.
I use Dropbox, and it generally works a-ok with Orgzly. That said, I rarely find myself using Orgzly - but it's invaluable when I'm on the go and need to check some info stored in my org files.
It used to have issues, but after couple iterations it seems to be working quite well now. Some time ago scheduled tasks even started to generate notifications on the phone, so now I find myself syncing more often just so that I can get those reminders when I expect to spend a lot of time away from my computer.
The only thing problem I had with it is that if I delete a file locally, and then sync Orgzly, it'll restore the file on Dropbox instead of picking up the delete. After having to re-delete some files couple of times I now remember to watch out for it, so it's not really a problem anymore.
I use beorg to get my org-mode lists on my phone. It works with WebDAV and Dropbox. The developer has also recently added the ability to edit documents on your phone (previously it was pretty much read-only).
To be honest I only really use org-mode and similar organisers in order to dump something out of my head ('close the loop' as I believe it's called in GTD parlance). Do you find it easy to update progress etc as you go?
With WebDAV on MobileOrg, I never really had these problems.