I had e28 M535i and now have e34 535i.
e28 is more fun, it had no body roll whatsoever (very very harsh ride for roadcar tho), once i did a line change in split second at 180km/h and it felt very under control and safe and just like i wanted, i guess some lesser car would have flipped over. She liked to kick her back like hell and i loved it. Also the acceleration was much better and she felt much more nimble overall.
The e34 is more comfortable and propably safer to drive, perhaps better built and i guess faster around the track.

Anyways i will buy some e28 again but only when i have enough money to afford a second car because well they are too old to be daily drivers specially where i live (salt is used to melt snow and its very bad for old cars body).