recommendations for 5 series year / model - in UK

I have just sold my 1995 E34 525TDS, and whilst it had a few problems which
I sorted, I really liked the car.
However, the replacement does not inspire confidence and so I am looking for
another 5 ? series and have
the following wishlist.
Diesel, Manual, reliable, age between 1997 and 2001 and a budget of around
GBP £8K or a bit more if justified.
I can do most work myself but do not have many "special" tools.

Can anyone point me to models to look for and those to avoid for ? whatever
reasons ?

I guess it may/must be an E39, but don't know much model history / years to
avoid / gadgets to go for etc..

Appreciate comments and suggestions

Thanks,

Nick