SheetCam is a winner in my book. Mach3 is no choice if you have an original CrossFire or you’ll use FireControl if it’s a new CrossFire. Either way, SheetCam is excellent IMO.
As far as CAD is concerned, if you’re doing mechanical parts, Solid Edge 2D is good and free, I’ve been using Solid Edge 2020 Student version (because I’m a 70 yr old student
and I’ve been messing with FreeCad which is truly free, but does have a learning curve. I’m slowly drifting toward this as I’ve been using this for sheetmetal, mechanical, laser, and 3D Resin printing.
If you’re doing Artwork then by all means get InkScape. It’s free and a good choice. Others are doing well with Affinity Designer (it’s $50 US) and of course, if you can stomach Adobe there is a collection of tools there…
If you like SolveSpace and it can produce DXF or SVG files then that will work as well if you use SheetCam as your CAM tool.