There are sound-dampened Cherry MX switches available on several keyboards these days, but the switches are unfortunately only in the linear Red or Black varieties. They have also been reported as being smoother than other contemporary Cherry MX switches.
If you don't mind spending a lot of money, any non-clicky PCB-mounted Cherry MX can be pretty effectively sound-dampened with
QMX clips.
However, there aren't many PCB-mounted keyboards around as almost every Cherry MX keyboard these days has also a metal plate holding the switches - and a plate is not compatible with the QMX-clips.
You could get a Cherry G80-series (except for the MX-board 3.0 or higher), but most models are a bit bulky. The first versions of the 60% keyboard Poker (but not Pok3r) also did not have a plate. There are also DIY keyboard kits around that allow PCB-mounting.
Similar clips that
are compatible with plates are available for a limited time, and at a higher cost, from Zeal PCs. He calls them "Zealencios". Those can only be pre-ordered, however and will probably not be available all the time after that either. The first run is shipping now.
BTW. The build of the keyboard case also has a large effect on the sound.