I'm in an unusual position, in that the locomotive I most badly want (ET&WNC ten-wheeler) has already come out. So, as the old folks say, I have no dog in this hunt...
I must admit a WP&Y loco would be great. I have zero need for one, but I've ridden the White Pass personally, so it'd be neat to see one.
A EBT one would be great as well, both have a 'modern' look seriously lacking from On30 at this time.
That said, wouldn't D&GRW engines sell orders of magnitude more than either of the above? Sure, Rio Grande is modeled to death for NG, but numbers don't lie...