You knew you were going to stir us up, uh kapitan?
The George Washington was nice and true she was the first boomer, but she was originally designed as an SSN and had to be cut in the middle to add the missile decks in order to get the first FBM's out on patrol in 1959.
In 1961 the first true FBM class (built from the ground up) was created and built at Newport News shipyard the USS Ethan Allen SSBN 608 and her sister ship the USS Sam Houston SSBN 609 ... I forgot which year I think it was 62 or 63 that both submarines were the first and only missile boats to fire a live Polaris A1 with an actual nuclear warhead on it exploding above a langoon full of old WWII ships somewhere in South Pacific making history and proving that it could actually be done.
So in my choice of the top 7 it would include these two boats for the honor of the best Cold War submarines
I think the USS Triton qualifies too due to her around the world vovage, but she was a of a kind dual nuclear power plant SSN.