Cubase: Nothing else offers the chance to highlight a portion of the wave file and apply a VST plugin to it along with a lot of very very good file management systems.

Logic: Awesome collection of native plugs and exceptional MIDI functionality.

Ableton: Great scratch pad, ****ing awful sequencer and fantastic live program

Pro-Tools: Digi002 or better. Amazing recording / mixing tool .. wanky MIDI compared to the others

Fruityloops.. top quality loop creation and compositional tool

Reason: Bloody brilliant plugin when rewired. I use it for one massive synth with 10 subtractors loaded up and spidered together

IMO of course....