Those are excellent suggestions that definitely comfortably fit in with my (very) loose definition of 'b-side'. In all honesty, of course, it would make much more sense to just use a term like 'non-album tracks' (a similar discussion was held earlier in this thread, too), but back in 2003 I already liked the symmetry of A Best - A Ballads - A B-Sides, and almost twenty years down the line I still can't help but stick with it
Another concept for the cover (in line with the Selection comps):
