I discovered Todoist shortly after, and stuck with it.
I think for me, personally, to get anything even more productive, I'd have to write it myself.
But I'm trying to collect notes on how I use Wunderlist and TaskWarrior. Maybe in a few months I'll have a better idea of my usage patterns and then I can come up with something that I'd love to use everywhere.
Do you have any ideas on what you'd like to write yourself? I could get ideas off of you. :)
Other than that, Todoist gets very little wrong (and they're constantly polishing the more mundate UX parts, which is also an important part of any frequently used app).
Their team has been often very responsive to my requests, and have also been working on integrations into other services (which is often a sore spot for 'cloud' services).