Having worked only in the first 10 years of the CTS, and 1981-1985 on the DSNG, I haven't had the pleasure of running many of the favorites expressed above. In '70s I got to run the 483, 484, and 487, the 3 K-28's and one of the K-37's. At that time, 484 was the squarest and best-steaming locomotive on the CTS, and had the best traction of all when the going got tough.
483 is dearest to my heart though, having been the first locomotive to run on the CTS, and my first locomotive. 484 is a close second; 487 had timing problems then, and had a troubling pound on the left side, as though the piston were hitting the cylinder head when she was working hard.
I never liked firing the K-37's much, as their fireboxes were longer and you had to keep the front fired much more heavily than on the K-36's to make them steam. But if you got it right, they would steam well and pull more than the K-36's.
I have especially bad memories of running the 497 in the early DSNG years. The managers were hot to get her on the road, and I had to take her out before she was really road-worthy. For her first few runs, the throttle and Johnson bar quadrants had not been rebuilt, and were so worn out that they would not hold a setting either of the throttle or Johnson bar. So you had to run with your left hand jammed into the throttle latch so as to try to keep it locked into its quadrant, while holding the Johnson bar hard with your right hand at all times, and using your foot to try to hold the lock into its quadrant so that it wouldn't jump out and the Johnson bar fly down into the corner! And now think of reaching forward doing that, while backing the engine and looking back for signals!
If that weren't bad enough, the tighter curves in the track had not yet been adjusted for the stiffer K-37's, so that the pony trucks would lift up their inside wheel off the rail several inches and sometimes actually derail entirely. That was especially exciting when it happened in the High Line.
One morning while I was switching the 497 onto the train for the next run, one of the throttle packing gland studs broke off from the boiler backhead, so that the packing gland was only holding on by the one remaining stud. This stud would bend ominously with the back-and-forth movement of the throttle rod through the packing gland, threatening to break off the remaining stud. I'll leave it to your imagination as to what would happen to the engine crew (that is, my fireman and me) had the remaining stud also broken. I had to argue with the management to get the 497 removed from service that trip and replaced with another engine.