Any deal breakers that are on your list
Respect, if they showed me respect throughout the relationship and in the end I would maintain some kind of contact. Otherwise, sayonara.
Mostly what I think would be best for me... and I'd say also what they think would be best for them. And then putting those together and making a decision.
I never bother being friends with an ex. Things tend to get too weird when a new relationship is had by one or the other, especially if only one person is in the relationship. Not only that, but new relationship people tend to be leery of having an ex as a friend. Better to avoid the aggravation all around - something happened to spur the end of the relationship itself, why try to keep the ghost of it around?