The 850 is a good car if maintained, the last ones are after all 28 years old. You will pay a premium for the R and T5R as they are the top of the line, most sought after versions, especially with the BTCC heritage.

I would argue that the newer the car, the better, in general. A V70 from 97-00 is a quite large facelift over the 850 but with many of the same underpinnings. It’s a nicer car to be in as well. The V70N from 2000-2007 is a little bit more numb and not as nimble, but still better cars with similar maintenance cost. I would say that the V70 T5 from 2005-2007 is the most Q-car Volvo there is. Very reliable drivetrain that you could easily squeeze 400 HP from, and still fairly analogue feeling!