Other than the standard idea of a cello tailpiece, there are some specialty tailpieces available by individual makers who attempt to change the shapes of the tailpiece to maximize different sound qualities. There are many of these so it would be impossible to list every single one for comparison, but ask your fellow cello players and luthier for their thoughts. Again, don’t expect big drastic changes. The right cello tailpiece is one made from quality materials with quality craftsmanship, and your luthier will have those.