I use a combination of Things.app, Notion, and Trello.
Fortunately most of my client work involves the use of Trello. Either I come onboard and institute a board/process that they can jive with or they have an existing board/process. That has been great. Trello is only as good as the person managing it, that’s important and methinks why a lot of people dislike it. I do a good job of managing Trello to fit the general framework of working and thinking that exists for each project or client.
For client projects Trello is the boss hog. Everything is stored there. Things will get broken out into sub-boards when necessary.
For personal stuff, it’s a combo. I use Trello to track things that have graduated from the research/idea phase into the action phase.
The research and idea phase I speak of occurs in Notion or more accurately on paper documents (no. 2, 2B Soft pencil!) scattered around my physical desk that eventually work their way into Notion. There, I enrich things with outlines and maybe full blown documents. For instance I used Notion to do a big documentation project for a client, exported as markdown, cleaned it up, and then forklifted it into their Github project wiki.
I also use Notion for all sorts of personal stuff. My homelab for instance is tracked there, with tables describing IPs/hostnames or hardware in the rack etc. The hierarchical nature makes it great to start low fidelity and go high fidelity.
I’ve got random article ideas there, some in outline and others in more detail.
Will come back and update this post with more detail shortly. Doing this via mobile and gotta jet.
I will echo afarrell though and posit that the tools are less important than the process. Determine the process and the outcomes before you choose your tool!