Motu

It's called BPM and includes a vast library of sounds and one wide possibility of synthesis and programming. It works both in stand alone mode and as a plug-in, (VST, AU, RTAS, MAS, both for Windows and for Mac OS X), and boasts a complete compatibility with other MOTU virtual instruments (yes can upload samples from MachFive, Ethno, etc.) besides to the normal "drag & drop" operations of both MIDI files and loop or audio file. Also includes a rich mixer section complete with effects of all kinds.