It's interesting and coincidental that you should present these two choices. This was my exact dilemma a year ago before I bought my 95 E320. The only exception was that I wanted convertible (E320 cab vs XK8 conv). I opted for the Mercedes because I thought the Jaguar was too exotic. Though the Jaguar styling may be more sexy, I was pragmatic. I put few miles on my cars and maintain them well so I keep my cars for a long time. I wanted a car where parts availability wouldn't be a problem. I like the fact the Mercedes sells a lot of cars and uses many common parts across the model lines. This means parts should be available for a long time to come. Plus, like the others said, Jaguar has a reputation of being tempermental, especially with electrical gremlins.
95 E320 Cabriolet, 131K