I assume this 80k would have to be spent on a *new* car? In that case, I'd have to go with a Benz.
I once worked at a Jaguar dealer (which was also an Audi dealer) and can say that new Jags are completely different cars from what they once were. They are well built, they include some pretty advanced technology, and they perform very well.
With the Jaguar, I think you can get a little more car for your money compared to a Benz. However, the Benz resale is higher. If you are one who considers a car to be an investment, the Benz is the only way to go.
I could care less about resale value because I think that it's foolish to think of a car as an investment, unless it's a '98 Porsche 911 Turbo or the like
I choose the Benz because I like their instrument layout and driving position a whole lot more than Jaguar's. The interior of a Jaguar (XJ8, XK8, S-type, and especially X-type) is waaaay too tight, and their use of space is very poor.
You sit more upright in a Benz, and it feels like the "belt line" is lower--something I really like.
-Joe