Buy Jaguar XJ or not?

Hello together…. i need a different Daily Driver. Currently i.a. the BMW 528iA from 1998. Which would have to give way to a Jaguar XJ if necessary. Namely a Model X300 (call it so or?), XJ6 or XJ8. Now the question: Are these weighings reliable? Jaguar is totally new to me, I have no idea about it. What are the classic defects? suspension, engine, transmission etc.? How about the costs? I pay for e.g. for my 5 Series approx. 580Euro insurance per year, at 50% Postage rate, partial cascade. When are the models recommended? So, first of all enough questions. MFG Mike