MilesBuzz! - The "What ..." or The "Which ..."? Grammar issue

In Miles Buzz, a lot of postings ask for a decision between different programs, credit cards, Airlines, other offers, preferences, etc.

Most use the word "What" to start the question. "What credit card . . ." What program . . . "

I think it should be "Which". Since we are asking for a choice of several discrete programs, or airlines, or offers, "Which" makes more sense to me.

Which grammarians out there have opinions? What are your opinions?

No opinons necessary. Just look up rules for grammer usage in a dictionary.

Both are interrogative pronouns. Which is used when there is a list or set to choose from. As is "Which credit card is the best one to use for earning miles?" What should be used when seeking information. As is "What is the best way to earn miles?"

Now I wonder which mod will close this out and at what time?

Now I wonder which mod will close this out and at what time?
Don't you mean what mod will close this out and at which time?

How about "which" vs "that," e.g. "I like the F seats which/that SQ provides."

Don't you mean what mod will close this out and at which time?

Me, at 5:25am Pacific Time.

Let's talk "miles and points"!