The E39 is more modern and refined in every sense, it is not for nothing that many rate the evoloution of the 5 series in the E39 being the best car ever made...
I'd say the E34 is wooden by comparison and this might be best described as being 5 years behind in technical know how. The E39 is an easier car to live with.
However the E34 has a character that either grabs you or it feels just old!
To me it is down to aspects like no electronic interference, the traction control coming out of a roundabout on the E39 is maddening! but no one can overlook the fabulous torque.
The E34 has a character of its own relying on a proactive driver who can easily explore wonderful depths whereas the E39 is slightly anodine and heavier in comparison.
Both cars should be celebrated for being in existence but for me the E34 has a raw soul that demands more driver input/involvement to extract the juice.
Legacy mentions the E30 M3 Sport Evo, several of which are advertised on
www.mobile.de - no. 600 - being the last for 65k euros!. This would have to be my favourite car of all time it has fun and thrills in spade fulls and have run one of these as a daily driver and track day car regularly at the Ring for 8 years (and an Evo 11 for 6 years before that) but whereas the M3 is pure go kart the E34 has such refinement and still each road drive can be an event, not so great on track.
God bless 'Motorsport' for the enjoyment in all the guises they provide us!