If there is a single class of steam motive power that better fits that descripition, I'll challenge anyone to name it...here's why.
The J-1 was a creation of a wartime emergency, a proven design from Lima, the creator of Super Power, fleshed out and built by the Standard Railroad of the World, in the ultimate railroad town.
After spending its first years in the defense of democracy, it toiled for the remainder of its career fueling the postwar boom that would make it obsolete before its time.
Unencumbered by the experimental refinements that would doom the duplex-drives, it would endure to make the trip to the steel mills with the I's, K's, L's and M's 15 to 30 years its senior.
While it's regrettable that preservation eluded the J-1, this also contributes to its mystique; small wonder that the reproduction of Pennsy's 1944 calendar was incorporated into PRRT&HS' response to the events of 9/11/01.