Get both!
If pressed, I agree with you, Nicolas, the Mercator is probably the one to get. It seems the more iconic example of VC's alternative time display watches. And I think the Saltarello is probably less to everyone's taste than the Mercator series. I love both models, however. The Saltarello is a bit funky, while the Mercator is poetic. I really, really, really hope to add at least one of these to my collection in future years. These are both at the very, or nearly the very, top of my wish list. Ah, but they seem elusive.
Best,
respo