luckymucklebackit wrote:...Go for the Bachmann model of the Type 3 (later class 37 ... the Bachmann one stands out as the best all round.
This aspect is part of the reason in my opinion why you are better going for the Heljan Hymek.
The Bach type 3 not only looks well because it is overall accurate, it seals the deal by performing. Bachmann's very competent 'Spectrum' mechanism has all wheel drive and pick up, and thanks to a 22oz/615g all up weight is good to pull the side out of a house. Reliable, quiet, smooth running from dead slow throughout the speed range, thanks to heavy flywheels in the drive line.
Heljan have a similarly very competent drive in their models, different in detail design but on the same principles. The same quiet and creamily smooth movement with excellent traction. (Their EE type 2 'Baby Deltic' BoBo are the traction champions on my layout, and I have read similarly good things for their Hymek model.)
Just my opinion, but these leave any motor bogie powered model for dead. Once experienced it is pretty addictive, and for myself the wish to have all the traction be of matching capability is a strong factor. Next challenge, make all the steamers get at least within spitting distance of that performance. (Happily both Bach and Hornby - as the majority suppliers of RTR OO steam models - do know how, and sometimes prove it in their products.)