The argument about "best" just doesn't have much meaning unless "best" is put in context. Different engines are built for different jobs.
A different example. Lots of folks here adore the NYC Hudsons, and they were very good at what they were designed for: high-speed passenger service on the Water-level Route. But bring them out here and put them on the roller-coaster profile of the Frisco or the Mopac, and they would have limped home with their tails between their legs while a much less glamorous (and maybe even homebuilt) 4-8-2 did the job with aplomb.
T.E., HP, driver diameter, grate area, etc., etc. are a set of variables that allow for excellent specialization. Those big articulateds excelled in the roles they were designed for, but, as just the pair of Big boys and Challengers demonstrate, they were not interchangeable.
