Org-mode inside Emacs (spacemacs). I was using OmniFocus few years ago, then I have switched to OmniOutliner as I have figured out that flexibility of form and not-seeing contexts/projects/etc I don't care when @work or @home works just better for me. So I have split those two areas in my life into different files and outliner was a more fitting for the job than a dedicated GTD tool. Then I have switched my MacBook Pro for a touch-screen enabled windows tablet and Emacs with org-mode filled the role nicely.