Scooter in the lower displacement segment. We have 123, 124, 244 and 498cc Scooters.
In the higher displacement segment the motorcycles advantage in maintenance and economy would imho outbalance the expensively added accessories (storage, weather protection).
But I don't see a rational reason for a higher displacement motorcycle. Scooters of the 250-500cc (single-with pillion) class are already nice touring machines.