I agree that, with annual fee credit cards, "to keep or not to keep, that is the question." The fees for one's card collection can quickly become quite large.
My current dilemma is Marriott. I had both Chase Marriott credit cards and AmEx SPG cards prior to the merger. Between my wife and I, and between personal and business accounts, we now have a large number of cards, all of which grant an annual "free night" certificate. So long as we get reasonable value from the certificates, I don't mind keeping the accounts open. But that is becoming more difficult. And it's still a bit soon after the merger to know if we will be able to use all those certs. In addition, Marriott's recently announced intention to soon introduce peak award pricing makes the calculus even harder.
I'm not trying to steal this thread, and perhaps this should be a separate discussion. With so many Marriott timeshare owners on this board, I would guess that others may have the same Marriott-branded credit card dilemma as I.
