In my glmodel project i support wavefront obj, milkshape ascii and .3ds models. Direct x mesh loader (.x) is in the pipeline.
http://www.noeska.com/dogl/glModel.aspx

It started out as in .3ds loader because of supporting detailed meshes, but it does not support bone animation so i added milkshape ascii support. But that only is suiteable for low poly models. So there is not one best easiest to use format. For static meshes .obj is also easy to implement. Best format would be the direct x mesh format. Allowing all. But i am sure about license restrictions from microsoft on using that format.
But with my project you can load all format in the same way and use them in the same way. It renders only classic opengl 1.5 way and there is an test version of rendering it using vertex buffer.