Are you meaning the dies are round or the part that will go in the blister pack is round? If you are making a package die for a round part you probably won't need 4 axis. As for what would be a good machine the answer lies in what all you want to do with it. I use Mach2 as my control, Rhino 3d as my 3d modeler and will be purchasing Visual mill for my cam program for it unless the new version 20 Of Bobcad/cam will do what I need. I machine in 4 axis and my current cam system is costing me money.
Tell us a little more about what you do and you will probably get a bit more info that will help you.