Definitely the E500 because it is such a legend and because it looks like every other W124 to the person who can't tell the difference (enlarged fender flares etc.). A wolf in sheep's clothing.

But I'd be equally happy with an E36 AMG. The 300E was often praised for its combination of economy and power, so I can imagine that an E36 AMG will be just as economical while at the same time delivering a more thrilling driving experience.