I used Wunderlist in its initial incarnation and loved the automatic sync across all my devices. But I moved away because there were a couple of features I needed it didn't support. Unfortunately I cannot remember which were these and it's difficult to say what new features are in W2, so I'll probably need to give it a try.

Meanwhile I've been using a combination of OmniFocus for long term task tracking and TaskPaper for daily tasks only. After using OF for quite a while now, it still feels like it doesn't really fit. Actually, OF makes me feel I'm misusing it, giving me an unpleasant feeling every time I have to open it.