I've been refining an Asana workflow for a few years now and am pretty satisfied with it. (I've used GTD in one form or another for nearly 15 years now, and spent the first 10 years searching for the right toolset to keep my lists organized.)

I don't practice strict GTD, but do use most of the elements, and I find Asana ticks nearly all the boxes for me (with just one or two quibbles). It's the first tool I've used that doesn't leave me either spending all day organizing or constantly fighting friction due to a mismatch between tools and workflow.

I was never quite comfortable with Wunderlist, though to be fair it's been a few years since I tried it. What about it isn't working for you?