You've pretty much covered the classics.
I would add:
THE LAST MAN OF EARTH.
If "The Last Man on Earth" seems a lot like "Night of the Living Dead there is a good reason for that. They are both loosely based on the book "I am Legend," which spawned the Will Smith movie of the same name and the Charlton Heston classic "Omega Man." This movie was truly ahead of it's time by a few years.
"Madhouse" is the same kind of role Vincent Price has done many times before. But it is still one of his best performances.
Kudos to The Last Man On Earth
! Not sure it would be one of my faves in the top 3, but if I had to do a 3-movie set, it would be:
House On Haunted Hill
The Pit And The Pendulum
Not that I haven't seen his other movies, I just like the fun factor of HOHH and Tingler, and chose "Pit" for a serious one because he was truly wacked in that one. Kudos to a young and pretty cute Barbara Steele too!