Formats to support for an offline 3D viewer

I'm working on an opensource offline 3D viewer and I'm wondering which format you would expect a CAD oriented offline 3D viewer to support.

Here is a list of the format we currently support, with various degree of feature to be honest:

.ply, .stl, .dcm, .nrrd/.nhrd, .mhd/.mha, .tif/.tiff, .ex2/.e/.exo/.g, .gml, .pts, .obj, .gltf/.glb, .3ds, .wrl

We are currently adding support to .stp and .iges, but it has not been merged yet.

Which format should we add ?