I know that Durer preferred Bellini over Titian [yet Titian's influence on later artists was profound (He was supreme in every branch of painting and revolutionized the oil technique with his free and expressive brushwork)]or Giorgion and that his 7 greatest paintings were destroyed in a fire in 1577 so we don't have his best to compare.  Bellini painted the surface roughly so as to catch the light and give a metallic finish - a revolutionary technique at the time."
Giotto has become the symbol of a profound renewal in the history of Western figurative arts, and of the first radical renewal since ancient Greece.
"He converted the art of painting from Greek to Latin and brought in the modern era" according to Cennini's synthesis fifty years after Giotto's death.  And don't forget that the decoration of the Scrovegni Chapel in Padua (between 1303-1305) has been universally recognized as the most significant and most paradigmatic creation of Giotto and one of the capital events in the history of the European painting.
Tintoretto may have studied under Titian and the artist who most fruitfully absorbed the visionary energy and intensity of his work was El Greco.  Henry James wrote of the stupendous Crucifixion: `Surely no single picture in the world contains more of human life: there is everything in it, including the most exquisite beauty.' but he lived and painted almost exclusively in Venice.
So it's kind of hard to say which was best except as an opinion.  Maybe Bellini.  Thanks for the opportunity to get that off my chest.  This has plagued me for quite some time.