What I'd really like from Sunset is a Santa Fe 2-6-2 or light 4-6-2. However the 2-6-2 failed to generate much interest when proposed a few years ago, so I am not laboring under false hope.
It would be nice to have a real Alco-GE RS2. There is a significant difference in appearance between RS2s and RS3s. However, both can be produced with the body castings being different, using the same frame and running gear, with variable underbody details.
Since Weaver ceased production, there is no longer an accurate scale O gauge RS3. The hoods of the Atlas and MTH models are too high, affecting the proper shape of cab windows above the hoods. Lionel has a good looking cab, but markets its RS3 with stamped handrails, in its ready to run line, instead of as a Legacy locomotive.
But I did say RS2, not RS3. I only mention the RS3 as it would be hard to market an RS2 without the more common RS3. Erie, Union Pacific, Lehigh Valley, Lehigh & New England, Seaboard, Delaware & Hudson, Great Northern, Spokane Portland & Seattle, New York Central, Frisco, Southern, Monon, Rock Island, Peabody Coal, Chicago Great Western, Detroit & Mackinac, Maine Central (and Boston & Maine?), New Haven, Canadian Pacific, and Santa Fe all operated RS2's. There were probably other buyers of the RS2, but those were all that came to my mind.