stock for stock, imo, if value is included, then the Lotus Exige wins. It is similar in weight to the early 911, but handles better, is more predictable, and is quicker and faster. However, hands down, the early 911 looks so much better. Beauty is not exactly the Exige's strong point, imo. My other choice would be the "S" version of the car we already have - the Cayman.
Money no object - I'd say the Ferrari Enzo.