As a conclussion :
In character animaiton:
- My first vote for *.x format for characters. (provided it imports bones, weights, vertex normals, uv mapping, textures. ) Any package can today export this. (Blender included)
- My second vote would go with *.md5. No experience with it, but is said to be wonderful and really pwoerful. The big advantage is Gmax exports it as well as Blender(gmax does not export weighted x files).
In multiobjects characters, level geometry, static items, weapons and vehicles animations:
-By all means if there's multiparts animations (ie reloading mechanism of a weapon, any machine with internals independent anims) then it's MS3d static. is also very good as keeps usually very well smooth groups/vertex normals info (hard edges(not that blender doesn't support this yet! You'd need to physically split those edges in Blender, break the mesh, with whatever the format))
-If no anim embeded, then...OBJ rocks as an standard and fully featured. V normals, vertex gorups, material settings, textures, uv mapping, etc. And editable as is ascii. Just a tagged list of coords.