How much do you want to spend?
Reaper is pretty solid. The personal license costs $50. A cool feature it has is that you can assign an LFO or audio signal to modulate every automatable parameter of the synth. Pretty handy if your midi controller doesn't have many knobs and sliders to assign to the soft synth's controls.
Zynewave Podium now sells for $50. Very cool software as well. Then you have the more popular (and more expensive) software like Sonar, Pro Tools, Ableton, Cubase. They are more expensive but they also include more extras like effects, synths, etc.
You can download demos of most of them (not sure about Cubase) and try them out. I think Cubase requires the use of a Steingerg key (usb dongle). This dongle is made by synchrosoft so you can also use it with certain Arturia synths (Prophet V for example) and Rob Papen synths that require a usb dongle. The CS-80V doesn't require the use of a dongle by the way.