I’ve been using MyLifeOrganized for over 5 years.
The hierarchical task structure in MLO is a key feature that prevents me from switching, since it’s not going to be implemented in Everdo. MLO does have several features I don’t use, but I can see how they can be useful to others.
Unfortunately MLO doesn’t have a Linux build, but it does work via Wine, albeit with occasional glitches. Its lack of end-to-end encrypted sync is a problem, so I only use the higher-friction local sync.