I've compared my '93 E34 with my girlfriend's '99 E430. The cars seem to have slightly different missions. The E430 is quick and handles reasonably well. The E34 is a slug off the line (even with the performance chip), but at freeway speeds, it outperforms the E430 by a country mile in terms of handling, braking distance - overall driving experience. Complaints? E430 - seems vague at highway speeds, brake feel is non-linear, strange arrangement of the shift box - "D" and "4" are in the same gate and inadvertantly bumping the shift lever can easily put it in the wrong place. Build quality not up to solidity of my '88 W124. E34 - a 5 Series with a 3 series motor? Sheesh. Little annoying problems a constant companion with the car - door lock actuator failed, leaving me locked, literally, into the driver's seat, head gasket replaced at 120K, struts replaced a little earlier, BBS basketweaves are a complete pain in the arse to clean.
I drive either car happily, but prefer my BMW. I think she prefers it too, as a driving experience.
2003 Dodge Durango SLT
2002 BMW E39 530i Sport
1988 Mercedes 300TE
2003 Chevrolet Suburban