Not really feature specific, but I've thought about this issue for a long time now. I personally want to move a central application where location of user data can be chosen (s3, dropbox, etc). Mildly considering building an opinionated app for myself and open-source for devs, and paid for non-technical people.

IMO, paper/pencil is great for spontaneous unrestricted flow and manual transcription has shown to be better for synthesis than typing. But the advantages of digital in terms of persistence and accessibility is just too great.

For me, the biggest issue of productivity apps is they don't distinguish between "timeful" data (tied to dates like deadlines or calendar events) and "timeless" data that are more for recall and knowledge store. That's why our tooling is fragmented between todos, calendars, storage, and editors (sheets, docs, etc).