As @creativespiral said, MIDI-OX for Windows, Sysex Librarian for Mac are both excellent choices (I use Sysex Librarian all the time, it's reliable and offers a lot of features to control the rate when using USB MIDI which are helpful to ensure reliability).
I own the SoundTower editor and like it just fine - it has lots of features, but it's very "clunky" to use, IMO, feels like very old style software, highly skeuomorphic and not particularly intuitive, especially with regards to the advanced features of the librarian, and I cannot find a manual for it anywhere, so there are some features I just don't use because I have no idea how they work or are supposed to work.
CodeKnob's stuff is very nice (I have the CodeKnobs VST, in fact) but I don't use it for librarian functionality so I don't know how well it does that.