Both S and Y are outstanding. But, to show that Y is better than S, you picked up a wrong example. From
http://amc.maa.org/a-activities/a7-problems/putnamindex.shtml
most of time, S team is in the top five, but Y is not.
Mu was a Putnam scholar last year, but he is the only one since 1989.
Keep quit if you know nothing about a specific field.