@BC1989 posted:To my eye, the Lionmaster Challenger does a more aesthetically-satisfying job at "shrinking" the engine down to a size so it can fit on O-31 tracks. Again, to my eye, part of the essence of the "look" of a Challenger is those number boards up top on the front making a kind of ship's-prow around the bell, which I don't see on the Railking Challenger. I also thought the leading truck structure on the Railking Challenger looked truncated in comparison with the more fulsome design on the Lionmaster. Basically, I though the Lionmaster looked more like what I wanted to see in a Challenger and I could get it with a fun special effect that is important to me.
This difference has been stated quite a few times over the years when this subject has come up, when comparing the Lionel Lionmaster and MTH RailKing Challengers. As BC1989 says, the Lionel version looks considerably better. Lionel did a much better job of resizing the locomotive and making the dimensions more realistic. If you don't want to spend the money for the more recent Legacy versions, the older TMCC versions are the same construction, and also are very good runners.
