Gateron Aliaz switches are extremely quiet as well.
The bump on them has a bit of pre-travel, then crosses the bump, and increases in weight as it approaches bottom out.

By contrast, my Zeal Zilents, drop off the bump almost immediately, and decrease in weight as they approach bottom out.
That feels better to me, but is a bit louder than the Aliaz switches, although still very quiet.

I run both of those with Gateron White springs in them, to lighten them up to 35g.