Best software for 3d printer modeling

If you mean software for designing your own 3D-printable models, the best choice depends on what you're making:

My recommendation

For most 3D-printing hobbyists, I'd start with Autodesk Fusion. It uses parametric CAD, so you can precisely specify dimensions, holes, angles, tolerances, etc., and later change a dimension without rebuilding the entire model. Autodesk currently offers Fusion for personal use under certain eligibility restrictions. Autodesk 3D Printing

If you want completely free and open-source, go with FreeCAD. It's particularly good for mechanical parts and runs on Windows, Mac, and Linux. 3D Printing

If you've never modeled anything before, start with Tinkercad. It's browser-based and uses simple shapes that you combine and subtract, making it very quick to learn. Autodesk

If you're making statues, characters, miniatures, masks, or other organic shapes, I'd use Blender instead. It's much better suited to sculpting and mesh modeling than traditional CAD. 3D Printing

If you tell me what you're planning to print (e.g. functional parts, RC-car parts, miniatures, cosplay, replacement parts, toys), I can recommend the specific software and a good beginner tutorial path.