To put in my two cents, if you can manage 36" radius curves, by all means go with the Williams brass (made by Samhongsa). They typically pull strong and smoothly; the gearing was good. The detailing is simplified but correct so far as it goes. Brass is easy to work with. Details can be added. I owned one, sold it, missed it, bought another. Have yet to upgrade it to Command Control. Stock motor can be a bit noisy; varies. Brass is a sound amplifier, anyway.
(FWIW, the smokebox front on the Williams is more accurate than those on the high-zoot 1:48 Lionel and MTH versions - Lionel and MTH packed so much stuff on theirs that their smokebox doors are too small.)
Paint those shiny tires on the wheels, subdue the rod and valve gear shine, Dullcote it. ERR Cruise Commander would be great, if that's on your list of possibles.