Under-appreciated / overshadowed North American steam locomotives

[Aurora SL 1]

I have just finished re-reading Jim Scribbins' fantastic book, The 400 Story and this thought has come to mind: 

The initial four E-2 Pacifics that were modified to run the steam-hauled '400'  - they became class E-2-a (oil burners, larger drivers, amongst other modifications - are very impressive machines. The diagram for the '400' must have been one of the most punishing in the U.S. in terms of demand for rapid acceleration and sustained high speed running. Yet, if it wasn't for Scribbins' book, I don't think I would ever have known how remarkable those locomotives were. Not only were they overshadowed by the Milwaukee Road's A class Atlantics and F-7 Baltics, I think they were also somewhat in the shadow of their owner's 'H' class Northerns and E-4 Hudsons. 

Anyone else have nominations for otherwise impressive and capable steam locomotives that were overshadowed by more 'glamorous' (for want of a better term) or simply better known rivals?