What are you going to be using this for? Commercial use, or home hobby use? What type of parts?
I've used DesignCAD since I think version 3 in Windows 3.1. Although I quit using it about 7 or 8 years ago (use AutoCAD now
), I've always thought DesignCAD was a great deal. It's much easier to learn than TurboCAD. And it's amazingly powerful for the price.
I've never even seen BobCAD, so I won't comment on it. But from what I've heard, research this option very carefully.
Like Robert said, get SheetCAM while it's free, and use it for 2.5D work. Add MeshCAM for 3D stuff for $100, and DesignCAD 3D MAX 15 for $90.
Before you buy DesignCAD, though. If you'll be using it with MeshCAM, make sure it can export models as .stl's, or make sure it's .dxf's are compatible with MeshCAM (.dxf's must contain 3D faces only- if you know what that means).
One last important thing. Don't just go and buy software because someone here (or anywhere) tells you it's the best thing. Always download a demo and make sure it will do what you want, the way you want. I read a lot of stories about people buying software only to have it sit on a shelf because it wouldn't do what they wanted to do, and they had to buy something else.
Do the research, and only spend your money once.