Help me find a better place for do tos lists?

What is your holy grail of to do list apps or tools?

Trying to get my productivity in order and listening to the Power of Now audio book and they talk about having one space where you can collect your to dos and anything that comes up.

I am looking for something

- that I can use both on my phone and (work) computer

- That gives me the option to cross things off and then they disappear but I can still find them if I need to look at them later

- where I can have different categories but also a good overview

- best case for free or with a solid free version for testing

So far I have used Notes on my iphone (I dislike that the crossed off things stay there and I cant automatically move something to a different category), Notion (Its to complicated for what I am looking for), Microsoft ToDo (dont hate me but just something doesnt sit right with me with that one).

I would looove to hear what you prefer!