With the addition of Delta Hotels, it's time to update the discussion on Marriott hotel brands I began a couple years ago with the thread
Using the above graphic from Marrott.com, here are the brands listed.
Marriott Executive Apartments
Marriott Vacation Club
Fairfield Inn & Suites
When searching the hotel directory, Bulgari is not listed, but Marriott Conference Centers show as a separate brand, keeping the total at 19. Feel free to include either (or both) in your list.
From the previous discussion, I don't recall that anyone has stayed at all 19 brands. How many have you tried?