This might stimulate some interesting conversation. If your locomotive roster were limited to just locomotives, what would they be a why?
My choices would be:
Santa Fe Warbonnet A-B-A EMD F3's: This is the first image of a locomotive that comes to mind when I think of model railroading
NYC Hudson 4-6-4: IMO, this is the most symetrical looking steam locomotive ever to grace the rails and is the first image of a steam locomtive that comes to mind when I think of model railroading.
While I run neither of these on my layout, I have a G-gauge USA chrome Santa Fe Warbonnet A-B F3's displayed on the mantle of my fireplace (they catch your eye as soon as entering into my living room) and the gold Lionel Hudson displayed in my book shelf (and you know the gold catches you eye quickly)