I feel like I've used it all - apps, plaintext, files+dirs, taskwarrior, ad hoc paper, bullet journal, org mode. I've used org mode many times over several years, but it only clicked for me as a system when I recently started using its capture templates and agenda views. If org-mode could be described as a system built on Emacs, it feels to me like task management with custom capture templates and custom agenda views is sort of a system built on org-mode. That probably makes it sound unnecessarily complicated, but it's actually extremely simple, fast, and reliable. I'm still using Apple's Reminders to remind me at 0900, 1245, and 1600 to actually check in with my system, but the system itself is working beautifully.