All diesels are becoming increasingly complicated in order to meet stringent emission regulations. You're not going to find a simple modern diesel but, for your mileage, I wouldn't be too concerned. Problems occur when people use diesels for regular short journeys and the diesel particulate filter (DPF) becomes blocked. For 25k miles a year (presumably mainly on the motorway), a modern diesel will suit your needs well and should be very dependable. A Mercedes-Benz C-Class Estate or BMW 3 Series Touring would be a lovely choice for 25k miles a year. Also consider a Volvo V90 as a comfortable, slightly left-field choice.