The 4-6-0 would be pretty good. I own one of those. I also have a few 40 footers or less cars for it to pull that will fit on the future branch and not look too bad.
Now I love big steam the radius for those is 24" minimum I may suck in the asile widths and make it 26" radius minimum.
But on my 2x8 shelf the 4-6-0, 2-10-0 and P2k 0-6-0 will be the ones making and breaking trains.
I consider 18" industrial and branch line (Logging, mining and quarrying)