I have had E55 AMG 03, it is basicly same car, but an M in Benz World
Well it depends, i had mine fully loaded, with keyless go, sat nav, ventilated seats, panoramic roof, airmatic, and so on. It hat better features then the BMW, however !!! The car i had was a computer on wheels, so as your home pc it did not like it to cold, not to hot, not to wet and so on, i constantly had some kind of electronic issue, this is suppose to be better or fixed from 04 ,but 03 and specially 02 are not that good. There is one more thing you should check that is EBC it is an electronic brake system that benz introduced in E-Class and on the first models (02 -04) the brakes could mailfuncion, there is a free uppgrade with the dealer, make sure that it is done.
If the car is not fully loaded then you have nothing to worry about, less electronic on 02 means less truble. However there is one problem that will remaine, E-Class blows the lamps a lot dont know why, but you will probably have to change plate, position and brake lights often.
Then there is ofcurse the style, i personaly am not a benz person, al do the car i had handled the road as any beemer would, i felt old in it, BMW is always going to be a better car

Hope this will be hellpfull info for you

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X5 4,4i-06 Current
330Ci Cab-03 2007-2008
MB E55 AMG-03 2006-2007
Z3 2,8 Roadster-98 2006-2007
X3 2,0d-05 2005-2006
320d-99 1999-2005