Apple recently updated reminders for ios 13 and macos cataina. It’s free, integrates with the apple ecosystem and has some fairly powerful features. It looked like it could replace my current todo app TickTick which I have a subscription for.
To get started though I’d have to migrate all my exisiting lists into reminders. There’s no import functionality so a big pain for anyone wanting to switchover.
Below is the code you will need to be able to import todos into reminders for mac and ios
Most other todo apps will allow you to export to CSV or other formats. However AppleScript seems awful at handling CSVs. I recommend converting all your todos into the format above in a text editor then run it in Automator.