My favorite is my Vision Line Challenger. I also have the Vision Line Big Boy (unpainted version) that is a close second. One of these days, I will get around to painting it.
I also have the PRR 0-8-8-0 that I fired up for the first time in a long time. Forgot that the smoke effects are fantastic, especially the blowdown "steam". I'm not a PRR fan, but this one is sure nice.
RAY