after owning both, an e34 and e39 - I'd have to say the e34.
They are not 540s, but im sure the differences are the same as they would be between the two 540s.
I get SO much more driver-satisfaction out of my e34 than the e39. The e39 feels nice and MUCH more luxurious and refined, but it quickly feels "boring." the sport package helps, but theres still something lacking. The turning radius is not as sharp, the car feels heavier and more unwilling to be able to handle sharp maneuvers (even though it WILL handle them almost as well as the e34) It just feels so "unhappy" I love them both, but if I had to pick just ONE, it'd be the e34.
Reliability is going to be very similar between the two assuming that mileage is also very similar. Parts for the e34 are dirt cheap nowadays and can be found anywhere it seems like (online that is) and the e39's suspension is a bit more of a bear to work on, but it's do-able still.
If I remember right, your coming from an e30. The e34 will be loads more luxury and refinement while still feeling "tight" on the road. The e39 will just be a flat out lux car in comparison to an e30, but may feel a bit heavy and "boaty" if you like the handling and feel of the e30.
the main differences between the two is that the e34 lacks refinement and modern looks in the interior,etc. If thats what your after - go e39. If your after a fun, but still very nice riding car - go for the e34. Drive both and you will see. And yes, e39s DO tend to feel tighter all around (usually), but keep in mind almost every e39 you come across will be a lot less mileage than almost every e34 you come across due to age, so thats a terrible comparison!!!
Good luck on whichever you buy, they are both amazing cars. Oh - and the e39 540 is a bit more powerful (4.4L vs 4.0L) and has the option of steptronic. When driving the car, you can't really FEEL the power difference, but if you watch the speedo / tach, you know it's their.
With this board being mostly e39s, (and many with a few exceptions have not even driven an e34) My comments will be an uphill battle - so theres some bias there. I suggest you drive both extensively.
Last edited by sp0rky; 11-26-2005 at 01:27 PM.