Part of the preference is the "Blue Comet Mystique," originating in the Prewar, deluxe Standard Gauge set that is the dream of many collectors. Though the MPC set is not the same by any means, the mere name attracts.
If you get either, don't expect it to fail in a hurry. A little maintenance, and it will probably outlast you. The association of MPC with junk is both untrue and unfair. I have a truly bottom-end MPC engine that has more hours on it than can be counted, has only needed a set of brushes and lube over the last 50 years, and which is the ONLY Lionel engine I own that has NO problems--unlike the two postwar and the several modern era (i.e. expensive, command, scale).
I like red, so I think the C&A set look much better, but that is simple preference. Neither is particularly realistic or scale, so be advised ahead of time. Both are attractive, generally reliable, and a pleasure to run.
