In the marketplace of file formats for 3D content, X3D has a tremendous advantage over all other formats by nature of its ISO Standardization, openness, and compatibility over 20 years. There are other formats that meet one or more of these features, including OBJ and FBX; however, X3D has not been a dominant or even significant player in the marketplace.
Maya is used for a lot of 3D modeling. Modelers frequently save their completed work in a FBX file. FBX is a proprietary format designed by Autodesk (check this). In addition to the model, it contains the textures, rigging, and animation. It is a very convieient format, if you have an appropriate library of other tool to unpack it. Blender is an open-source modeling program. There is an FBX importer in Blender that handles many of the features and variations of the FBX format.