For me it would be:
1966-1968 Lambretta SX200 Uber rare and probably the BEST Lambretta ever made.
1974-1979 Vespa Rally 200 What scooterist wouldn't want a Vespa Rally?
1977 and up Vespa P200 This would be my daily ride.
For me the first two would be the equivalent of the 1961 Ferrari 250GT California Spyder from Ferris Beuller's Day Off.