Synonyms for A-one:

adj.

all (adjective)
first-rate, tiptop, ace, super, tops, topnotch.

n.

bully, prime, good, excellent, capital, splendid, superb, fine, blue-ribbon, swell, quality, first class, dandy, banner, champion, great, brag, boss, topflight, top, tophole, terrific. a-one (noun)
superior, ace, tiptop, super, topnotch, first-rate, tops.

Other synonyms:

blue-ribbon, topflight, tophole. first class. champion, dandy, prime. great, fine. boss, splendid, terrific. quality. first class
excellent.
Other relevant words:
capital, splendid, prime, terrific, great, brag, blue-ribbon, champion, dandy, swell, tophole, first class, boss, topflight, fine, bully, banner, excellent, superb, quality, top.