Honestly based on experience with both cars (we had both for 4 yrs and we decided to sell the w210 and keep the e39), go for the E39...that's no joke. Assuming both are either stock or both with their respective sport packages, you should test drive both cars. And there you will really really feel the difference between the 2 cars. The E39 is really the performance oriented luxury sport sedan...hands down. The w210 is just simply a luxury sedan period. Don't get me wrong, I do like both cars but the e39 is really different...once you drive it, you'll know what I mean.