You did not provide enough info for anyone to give you an educated opinion. What is the condition of the two bikes and their components? How much wear and tear does each have? What level of Campagnolo components?
Cannondale and Giant both make decent frames.
If it were me and all things between the two bikes being relatively equal I would choose the Campy equiped bike but I am partial to Campy. Campy tends to be rebuildable where as Shimano tends to only be replaceable.
But there are a lot of variables in making this decision.
Rans Rockst (Retro rocket) Rans Enduro Sport (Retro racket) Hase Kettweisel Tandem (redundent recumbent), Merin Bear Valley (The gopher).
You're the one who suggested the car comparison. So what kind of car do you own? If it's an older Porsche, get the Cannondale because it'll have more panache. If it's a newer VW, buy the Giant because it'll probably be more reliable.