Mach3 is awesome, (it is made easier by the fact I use fanuc based Gcode all the time at work.)
It`s constantly being improved upon with an already staggering amount of features, I have a shuttlepro handheld pendant hooked up for selecting axes and manual jogging etc, even got a webcam setup with a viewing window in Mach3. The support available is phenominal, yeah I rate this software top class.