In my experience, OF3 looked very attractive but just wasn’t worth the money and I unsubscribed before my first year of use was up - lots of glitches and support tickets for setting it up, very clunky interface, syncing took ages and delayed shutting down my device, and the web-based version was an utter rip-off: unusable interface and slower to load and respond than the days of dial-up.
After lot of experimenting with Todoist, I settled on a setup which works well for me (though I use Things 3 for my professional work). Todoist, despite recent bug issues after their Foundations upgrade last year, is very slick, fast, and customisable. I can capture an entire new project including any sub-project along with its next action, context and due date in a single “quick add” view (a combination of using #, /, @, and smart date recognition); and I’ve recently discovered a world of flexibility with the filters tool (I use labels for contexts when inputting next actions, but I use filters to summon those contexts, which allows me to filter out actions which reside anywhere in a “someday maybe” parent project (makes it easy to switch projects between being active and non-active by simply moving them in and out of it), as well as combine multiple labels to make the equivalent of parent > child contexts - e.g. the context labels “@livingroom” and “@kitchen” can be combined into a filter context called “downstairs”.
For reference in Todoist, I’ve made a parent “project” called “Reference”, with alpha sub-projects (“A”, “B”, “C” etc), and then I use the “sections” feature if I need to make a collection within any of those. E.g. #C /Covid. Sections are limited to 20 per project, but I know that if I overspill then I can create more projects (eg C2 etc).
