Mountains are generally measured from sea level, in which case Mount Everest (29,028 feet; 8,848 meters) is the highest.
Hawaii’s Mauna Kea, though, rises an astonishing 33,476 feet (10,203 meters) from the depths of the Pacific Ocean floor. Measuring from base to peak, Mauna Kea is the tallest mountain on earth, of which only about a third is visible above sea level. A third way to determine the world’s highest mountain is to measure the distance from the center of the earth to the peak. Using this method, Chimborazo in the Andes triumphs. Although it stands but 20,561 feet (6,267 meters) above sea level, its peak is the farthest from the earth’s center taking into account the earth’s curvature.
(from: http://hypertextbook.com/facts/2001/BeataUnke.shtml)
Anyway you measure it, in altitude or mass or climb rating, Everest is clearly among the great aesthetic wonders on this planet. Within each minute the clouds shroud the mountain in endless variants of beauty on this dramatic and sublime sculpture.