The 979 is undoubtedly the most iconic. A great, lightweight, all-around bike--though not at all stiff. Know that it is an aluminum frame if that makes a difference to you. It went through minor variations but basically stayed the same from 1979 into the late 80s. They made tens of thousands of them and can be found pretty easily with patience. If you find a Vitus, a careful inspection would be in order, since the tubes are glued/epoxied together and have been known to separate--though the number of such incidents is low enough not to scare you away from the model.

They also made several very nice carbon frames with alum lugs and carbon tubes. The models were numbered something like Carbone 3, 7, 9. I think the Carbon 3 came out around 1985 and the Carbonne 9 around 1987. Forum member Chombi has a beautiful Vitus Carbonne and would likely know.