What are the best questions from Stack Overflow that should be posted on here?

One category would be questions that are useful, but that are now out of favour on Stack Overflow.

They are either deleted (or even hard deleted, like the boat programming one - see below) or risk deletion if there is enough attention on them, such as list-of-X questions (no definite answer - the prototypical one is What is your favourite programming language?) and part of the history of Stack Overflow (e.g. referenced to in the folklore of Stack Overflow and in podcasts):

One category would be questions that are useful, but that are now out of favour on Stack Overflow.

They are either deleted (or even hard deleted, like the boat programming one - see below) or risk deletion if there is enough attention on them, such as list-of-X questions (no definite answer - the prototypical one is What is your favourite programming language?) and part of the history of Stack Overflow (e.g. referenced to in the folklore of Stack Overflow and in podcasts):

Another category is the silly questions (that Quora does not object to) or ones which produces silly answers with some entertainment value, like the now famous boat programming one, What do I need to do in order to be a programmer out at sea?, (hard deleted at Stack Overflow, but available on web archive):

(The main attraction of getting 10,000 reputation points on Stack Overflow is the ability to see these deleted questions.)

I don’t see the point of posting questions from Stack Overflow here or the other way around unless you are the author of a question and hope to get more answers on the other site.