@metta I too looked at Amazing Marvin. They lacked a decent iPad app at last look. Nearly bought in on a life sub.
Have seen folk integrating Ayoa (Ayoa.com) & TheBrain via Google Calender - both visual mind mapping tools, might work for you? Over here in the UK, Dyslexic/Autistic Uni students often get an Ayoa sub for free, I keep looking at it for myself. Looks though it might flourish into a wonderful app, in due course.
Did try Todoist. Hate their sub task structure, kept loosing stuff. No clean Evernote Integration. Though it’s integration heaven, with everything else.
Ended up with Nozbe. Don’t sync Nozbe’s Google Cal, with TheBrains’s Keep them distinct.
I find a GTD style work flow helpful, so the 50,000-30,000 ft view is TheBrain, 20-10K is Evernote & Runway is Nozbe.
Information, knowledge, Thinking, high level planing in TheBrain
Focused relevant information summaries, Mid term planning in Evernote
Tasks & Information for here & now, maximum 3 months ahead in Nozbe.
So @megaquests kind of a tangential response, but maybe helpful in my description of how I use TheBrain to tame chaos & as a high level task list.