Your advice when buying a car

Hello, I’m new here in the forum. I drive a lot by car, mostly professionally. I drive about +/- 50,000 km a year. My current car already has too many kilometers and this must probably wait too much and too expensive, therefore I urgently look for something newer. However, I think all new cars are not worth it, but rather an annual car or a little older. Actually, I was satisfied with my low-consumption old A-Class, but these compact cars are unfortunately in maintenance I can’t decide from SUV or Kombi. Kombi probably has less consumption. I also have the new Mercedes C-Class T-Model with a diesel engine in my eyes or an Opel Insignia Sports Tourer with diesel engine at Kombis. As SUV I like the Mitsubishi Outlander. I want to be a value-stable car as much as possible by driving a lot, but the maintenance costs also have to be within the scope. What do you recommend?