I definitely agree that you should only consider the 325i or the 850.
For the 850, it has to be the T5 or R. The NA ones are just too sluggish, even the GLE (20V).
My family have owned a few Bimmers and Volvos. We had a 328i (E36), Volvo 850T5 and 850SE. I never tried the 325i, but my guess is it cant be far from the 328.
Among these cars I drove, I found the most fun to drive on the streets was the Bimmer 328, followed by the 850T5. Both were equally powerful and fast! Nice handling too.
But with a RWD on the BMW, there is so much more you can do! However, some skills would be required!!! :P
If you get a lousy driver like me accelerating at a sharp corner, the car will bound to spin out! The rear of the car is light and many unexperienced drivers can really lose control if driving too fast into corners! :P
From my past experience, I approached a U-turn at approx. 120kmh. Was driving about 160kmh and braking hard! I had bad judgement, so reached the turning at too high speed! The 850 skidded slightly and managed to make the U-turn successfully! (I thought I was gonna die and my passenger was left speechless) haha
At the same corner, but this time in a 328i. I was not concentrating and driving too fast. I reached the U-turn corner at around 110kmh, braked hard and tried to make the turn. However, bloody back of the car skidded too much and spurn round. The car hit the darn curb and flew to divider!!! Damn lucky I did not die!!! :P
So if you ask me, I would choose the Volvo. haha! It is a safer car! Also more comfy and spacious! ;)
However, if you really like adrenaline rushes, lotsa excitement and you have nine lives....go for the Bimmer! Really fun car to drive! hehe
Ps. The Volvo 850 have nice sound systems. RDS! ;) For me it is nicer than the BMW 328.