Another good reason for Diesel is, just like mdb found out, they can be modified easier than gas. And with a diesel, when you modify it, you get better fuel mileage, and don't usually hurt the longevity at all. The thing I like about the Cummins in my Dodge is it is built for considerable more power. They seriously detune it in the Dodge to protect the rest of the drive train. So with minor modding, the engine is capable of much more!
How can you beat better fuel mileage, more pulling power, longer life, easier to modify for more power, and better resale value? True they do have more oil capacity, but the more oil an engine, any engine, will hold the better as far as I'm concerned. And other than that, maintenance is a snap!