I use the windows version of RoyalTS at work to admin the servers but trying to do less out of hours work at home so haven't tried the Mac versionAfter struggling with CoRD and the Microsoft RDP app for years I stumbled upon RoyalTSX. I can't sing this app's praises enough. It's saved collections, settings, and FreeRDP implementation work really well. It also doesn't crash all the time like CoRd did.
I'm honestly surprised more people don't know about it.
http://www.royaltsx.com/main/home/osx.aspx
That kind of sounds like a shill, but it is really great.
The windows version does have a lot of nice features though, so if I did need a client for OS X it would probably be my first stop.