WordNet sense 1 (model of excellence or perfection of a kind; one having no equal):

apotheosis, ideal, nonesuch, paragon, saint, nonsuch

WordNet sense 2 (eminent beyond or above comparison):

matchless, one, peerless, unmatched, unrivaled, unrivalled, unmatchable

WordNet sense 3 (such that comparison is impossible; unsuitable for comparison or lacking features that can be compared):

incomparable, uncomparable