Which engine for V90CC?

Moin together, in advance: I have some respect for the small, high-charged engine in terms of stability and also tend more to the diesel. Yearly driving power 15-20 tkm (experience value) , but can also be more (not predictable). We drive our cars mostly up to 200…250 tkm mileage. It should definitely be an automatic. How are your experiences with the engines D4 or D5 – what about the T8 – is that a serious alternative? 6-cylinders no longer exist, so I see that. Merci in advance -mgw