The most durable and the cheapest to run would most likely be the direct injection, turbocharged engine. Lesser delicate sensors to fail on you means lesser headaches in the long run. If it is turbocharged and intercooled, it should give good power too.

Commonrail direct injection, turbocharged engines should ideally be the most powerful and fuel efficient. Hyundai's 1.5L U-line engine found in the Accent, Getz and Matrix, as well as Toyota's 2KD-FTV in the Fortuner, Innova, Hilux and Hiace are examples of this. But it still boils down to the engine tuning and driving style. But these can incur very expensive repair costs if you neglect its maintenance or something inside has reached the end of its life.