I can't speak for solidworks, as I have never used it. Then again, it's not in the thread title
I cannot stress how much I prefer Inventor, especially for the applications that we are using in FIRST. I have used AutoCAD outside of first (designing test fixtures), and I felt a bit limited because my designs were 3D and lacked the flexibility that sketch constraints in Inventor have. AutoCAD was just not built for assemblies, either. With that said, AutoCAD does do a lot better than some
Other CAD programs than what I've used.