Best Extension for solidworks file
2 Answers
It depends on what you'll do with the model...
If you're not going to use the files in a direct way (i.e. a proof of concept, an animation, a rendering, a project you'll never make), native SolidWorks file formats are the best option as they'll preserve the whole feature tree (SLDPRT).
If you're going to 3D print the model, you'll need a file format that works best with mesh files (STL, OBJ, AMF, 3MF).
And so on...