The only thing more volatile than a can of gasoline and an open flame is what happens when you put a diesel geek in a room with a gasoline junkie. The diesel fan will point out that his fuel doesn't explode, it just burns slowly. In return, the gas freak will accuse the diesel fan - and his fuel - of being boring.
At the risk of angering both sides, we say that neither is the "better" choice - any allegiance comes down to personal preference. It's true that diesel engines are more efficient, but that benefit comes at a cost - they're pricier to build due to heavier-duty hardware, and to be clean and competitive on power, they require extra equipment like turbos and exotic fuel-injection systems. Then again, gasoline engines are increasingly using similar technology, so the divergence between the two approaches becomes less dramatic with each successive generation. Some powertrain engineers predict that there will be minimal efficiency differences between the two in the next decade.
One thing that won't change is the way the engines feel to drive. For a host of reasons, diesels are reluctant to rev beyond 5000 rpm, so they're aggressively turbocharged to make impressive torque over their limited rev range. They're happiest lugging around heavy loads at relatively low speeds.
Modern gasoline engines, on the other hand, use tricks such as variable valve timing to generate flat torque curves over a broad operating range. They tend to be smoother than diesel engines, and they also sing a much sweeter song - one sometimes loud enough to drown out the complaints from the diesel guys that gas engines are sucking the planet's resources dry.