As someone who has used .STL files for over 10 years, I haven't even considered using any other format for 3D Print files, with the exception of the occasional .OBJ.
In a typical 'Judging a book by its cover' situation I was quick to dismiss .3MF as an option, mainly because of its connection with Microsoft/Autodesk/Dassault etc...
But after accidentally exporting a model from Fusion 360, I may just stick with it!
What is the .3MF format & why it is better than STL?
3MF or '3D Manufacturing Format' is a relatively new, XML based file format, created by the 3MF consortium. Its also completely open-source. Free from royalties, patents and licensing
Unlike STL files, 3MF includes much more than just a bunch of tessellated triangles. It includes Scale, Colour, Material, Texture & Multiple Independent Objects. It also generates a thumbnail preview, which can be changed to a high resolution render if required.
It uses the same compression as a ZIP file, so the file sizes are much smaller. Compared to a Binary STL file with the same settings, it is over 3 times smaller in file size!
But one of its most 'Solid' features, pardon the pun, is that it will ALWAYS produce manifold objects! No more holes or overlapping features!
For more info visit: https://en.wikipedia.org/wiki/3D_Manufacturing_Format