While I don't own one (yet), I won't disagree with the Topre recommendation based on my research. Top notch quality while remaining quiet. It shouldn't bother your colleagues and will give you a quality experience.
I will also suggest, however, some certain lines of Keytronic. For instance the 3600/3601 and the Eurotech-C which I do personally own. There's a thread here about how these Keytronics are surprisingly good, with some people who have both claiming they are "80% of a Realforce". I don't want to start that debate again, but they cost 10% of what a Realforce does, they are quiet, soft landing, thocky (although with a little bit of cap ping on release), models newer than 10 years old or so have variable weight keys just like the Realforce and the typing experience is actually alright. I think I'm faster on one of these Keytronics than on my model M. We'll see how it compares to the Filco w/browns that I have in the mail somewhere.
Consider seriously whether you have any concern about others "borrowing", stealing or damaging your keyboard - intentionally or accidentally - because they don't realize it's a $250 personal item sitting on your desk. I have an office with a lockable door and that crossed my mind when I think about the possibility of getting a Realforce for the office.
My model M has a label on it "PERSONAL PROPERTY" and a lot of people say "who cares? It's a crappy old retro keyboard from a dumpster!". And this is about a model M which is clearly different in terms of sound, weight and appearance. A Realforce looks like any other plain jane keyboard out there, unless you get one with blank caps or something.
