> If you don't care about it, then pen and paper does seem to be ideal, but smartphones have a major advantage of portability.
For me, apps are a non-starter because I don't trust them to not collect and sell/exploit my personal info. Even if they insist there's zero telemetry collected because they don't care what types of tasks their users most often use the app for, a change of owner/management can change that situation without notice. The last place I want something like that is in the cloud.
I just assume they all are collecting data, not much that they can use that for besides ad targeting.
I do use Diary(The one of F-Droid) synced with SyncThing for journalling at the moment, to avoid any subconscious censorship I might give myself with a cloud app, but even then, it's not like I'm doing anything super private very often (Although I recognize that there are legitimate reasons to hide things including just not liking spying)
> I just assume they all are collecting data, not much that they can use that for besides ad targeting.
That's far from the truth. Depending on how detailed your task descriptions are. Your health insurance company could track how often you do or don't check your "go to the gym" tasks and if you miss too many days an algorithm could raise your rates since you're living a unhealthy lifestyle. They won't tell you why it happened. You bill will just go up. Your future employers could buy up that data and use it when making hiring decisions. So could a landlord.
Not only are you documenting for them all the things you struggle to do without reminders, but you also give them a list of all the times you've failed. That data could easily come back to haunt you in a court room. It could be used in a custody battle or divorce to show you are undependable and irresponsible. In auto accident if your records show you repeatedly failed to perform maintenance on your car it could make you more liable.
The problem with all the data being collected about you is that you can never know what it will be used for, but you can absolutely be sure that it won't be limited to ads and it will never go away so it can be used against you for the rest of your life.
You'll never know who has access to your data or what will prejudice someone against you. Best to keep as much data out of the hands of others as you can.
For me, apps are a non-starter because I don't trust them to not collect and sell/exploit my personal info. Even if they insist there's zero telemetry collected because they don't care what types of tasks their users most often use the app for, a change of owner/management can change that situation without notice. The last place I want something like that is in the cloud.