I own all three...MQP is considerably quieter. There's no "clack" due to the dampening, and there no mechanism to create a "click" sound.
The difference between clicky and tactile Alps switches is actually a lot more subtle than that. Tactile switches have two additional folded tabs in the leaf that stop the leaf being pulled forwards when the slider snags on it. It's the release from this pull forward motion that causes the click (a pressed bump in the leaf strikes the inside of the case), and blocking this action leaves the switch as merely tactile. Sandy used to have some nice diagrams of this, although really we need some lethal squirrel animations, which might help analyse where the scraping occurs in tactile Alps switches as a result of the leaf being held firm.
Pedantic post for the day ;-)
The clack of plate-mounted MX switches though is very high pitched and piercing, and I don't know why. Plate-mounted black Alps CM doesn't seem that much quiter, but the frequency spread is much wider and the whole tone is overall much deeper, so it's distinctly less bothersome.