After moving in and out of different things like workflowy, gdocs, dayone, notion, slack, discord, trello...I've been increasingly using just .txt and .csv files for the past half year or so.
Especially if it's just me working on my own, the benefits of any service aren't outweighed by the cost of later having to extricate myself from some startup's proprietary system.
@Mischa do you have a system? Todo.txt?