Basically, if you could restore up to 10 presently preserved steam locomotives in North America to operation (not counting the ones that are in the process of being restored) which ones would you restore?
Some contenders for me are:
SP 4460 (Run it with 4449) N&W 1218 N&W 2156 (make all the big 3 operational) CN 6400 C&O 2-6-6-6 #1604 Maybe a second Big Boy The C&O Yellowbelly at the B&O museum.
Sentimentally, I'd go for PRR 4483, the I1sa that used to be on the front lawn of the WABCO plant in suburban Pittsburgh and is now at a western NY state railway museum. This, in multiples, was what the steam locomotive era was about! But practically… Once we have a locomotive in working order, we'd like to see it work! So, we ought to choose a locomotive that could pull passenger excursions, and maybe the OCCASIONAL photo freight. So: we ought to be thinking of small to medium size passenger or mixed-service types. So, having lived in Pittsburgh when I became a railfan and so being to some degree a Pennsy fan… How about the E6 Atlantic that's at Strasbourg? (I think there's already a project to restore a G5 Ten-wheeler, so if you also restore an H-8/9/10 Consolidation, you'd have a wonderful educational opportunity to show how the same steam power plant could do different railroad work: those classes all had the same boiler. But in the interests of having something we could see operate regularly, do the passenger power first!)