The OBJ file uses a way to describe faces I've never seen before.
Blender accepts it but not Sweet Home 3D and probably other software. If you look at OBJ file, you'll see lines starting by f and followed by vertices numbers and // like:
Normally, this line should be written:
// should occur only if followed by texture coordinates index.
It would be nice to report this issue to Wings 3D, because it should be easy for them to fix.

The 3DS file works fine in Sweet Home 3D 4.5 Beta.

In all formats, the mirror texture doesn't appear but this might be due to the fact that you didn't export texture coordinates.