If your only consideration is render time than triangles are the fastest. Quads and ngons are converted to tris when rendered.
Cube 1 made up of quads: (6,144) faces, (12,288) tris.
renders @ 2:22:88.
Cube 2 made up of tris: (12,288) faces, (12,288) tris.
renders @ 1:59:99.