Of that group the st gaudens $20 is one of the most beautiful coins ever struck and the only 20th c coin I collect a close second for Morgans I like their design and easy collectibility in hi grade (tho I make it hard by trying to get all the cc morgans in unc)
US colonials (Constellatio Nova, Nova Caesarea, etc) and Bust Halves. If I had to choose from the original list, it would be Lincoln Cents, although I don't consider them "classic" coins because they were minted post-1800s.
What , no Bust coinage on the list ? I'd say Bust halves , out of the choices given it's a tie between the SLQ and the Mercury dime . I love the original design of the SLQ best but when they changed it , to me they wrecked it . So Type I SLQ . Mercury dime 2nd Lincoln cents original design 3rd .
Those are all beautiful designs, but the Saint Gaudens double eagle is my favorite US coin design. Walking liberty is a great one too.