I hope @bob2 does chime in, but I think his preference is for something other than a "1" in the 3rd position, which designates more powerful rare earth magnets.
I prefer the smaller Pittman 8000-series motors which will rev to 10,000 RPM. Unfortunately, scale die-cast steam locos even to this day have toylike gear ratios that work best with a slow-turning motor. The way they're designed, it's nigh impossible to install a different gearbox, so the choice of motor ends up being a compromise to fit the existing system. (Using a 24-volt motor is another trick to keep the RPM in the right speed range, and usually nets smoother starts!) Speed control was just a high-tech band-aid that came along at the right time and saved companies the cost of retooling.
Just once I would like to see someone get everything right: Top-quality motor in the firebox, big flywheel, separate worm shaft, ~30:1 ball-bearing gearbox with a torque brace, and replaceable wheels and axles held in place by pedestal binders or a "bottom plate." In 2-rail O scale, Lobaugh, Max Gray, US Hobbies had all of this figured out by the 1960s: a robust design that gives hobbyists ample opportunities for repair and customization. 60 years on, it hasn't yet made the jump to 3-rail die-cast 
The only thing that will entice me to buy another one is to build something better than what I already have!
