The answer to the question depends on what measure of efficiency you are looking for. In terms of stability, a sphere is less efficient since it can roll away!
There Isn't a shape bigger than the Icosahedron.
A dodecahedron
A nonagon (9 sides) for example.
Icosahedron can be bigger
It has flat sides to balance on, a sphere just rolls around.
There are several but there is one that comes to mind that has 20 congruent triangular faces called an icosahedron.
A sphere.
Apples are more efficient than coffee in this case.
Yes. Bird lungs are more efficient than mammal lungs.
Gas central heating is more efficient than electric.Open cast mining can be more efficient than deep mines.
earth
sphere