I think the correct answer is: all of the above.
we all want a single go-to, but even the favorite place will be out of one item on your list, and you will then need alternate plan B.
once you find the specific item you want, perform a dedicated search for it and I think you'll be surprised at the range of prices for the identical item. shipping, availability, and general user friendliness may also weigh into the final decision.
the Bolt Depot
https://www.boltdepot.com has been my first choice for general fasteners for years, an I live less than a mile from west marine. for the price of a dozen w-m fasteners, I can buy a hundred at b-d.
edit: I just clicked the link to make sure it worked, and see that there is now a BD hat. i'm tempted, and I never advertise.