AutoCAD is undoubtedly the most popular and powerful CAD modeling software. But as a commercial software, it is really, really expensive. FreeCAD is a free, open-source, cross-platform and general-purpose 3D CAx (CAD, CAM, CAE), PLM modeling tool specially designed for home user/hobbyist, experienced CAD user, programmer or educator.
Rhino (full name: Rhinoceros, AKA: Rhino3D) is a lightweight but extremely powerful advanced 3D modeling tool with a lot less hardware configuration requirements. Don't dismiss it, because it contains all the NURBS (Non-Uniform Rational B-Spline) modeling functions. As a matter of fact, many users often use it to perform modeling, and then export high-precision models for other 3D software to use.