I think it comes down to how many miles you do. A diesel will give you better fuel consumption. But, and it's a big but, despite the manufacturers' best efforts a diesel is simply not as refined as a perol engined car. And frequently, although the torque (or power) at low revs is better with a diesel, they normally fall down on power (or torque) at higher revs and they don't rev so freely. The last was a big disadvantage when I had an automatic Golf diesel. The auto simply didn't match the engine.