If this is to be a city bike instead of long-distance road bike, their performance differences will likely be minor. Go for the one which speaks loudest aesthetically to whoever will be its eventual rider, after eliminating whatever doesn't fit, of course. At first glance I'd say the Olympic Royale, but it's hard to say without seeing them in person. Lugwork isn't visible from 30ft, paint color is.

As for downsizing in general, I'm stuck on the question of which bike to ride for which purpose. We can't see the future, can we?

In any case, your question isn't about N-1, it's about which N+1.