Economy being the huge factor it has become since the rise in gasoling prices, today it will cost a an arm and a leg to fill up your gas engined vehicle with fuel, even if you don't own a giant SUV.
So, when it comes to the price of fuel, the diesel seems to be the least expense engine to run, and the diesel fuel will take the vehicle farther than gas will in a gas engine vehicle.
Today appearances are almost as important as the engine in a car. The diesel, as noted before, is loud and it does usually have black smoke streaming from the exhaust when the car is throttled. It is not a flaw with the engine, it just means diesel fuel is dirtier than gasoline.
Gas engines are more improved by a tune up than a diesel engine is. A large draw to the diesel is the turbo power it can deliver.
A good match is made when you compare a turbo charged diesel and a gasoline engine for their power. That's why most diesel cars today come turbo charged, its a way to keep up with the gasoline engines made today.
Now for the hard part. No one can make the choice for you. It really depends on which is the best engine for you. Decide what you require in your vehicle, and then think about which will deliver the most of your requirements.
Power? Tunable? Gasoline engine.
Power? Torque? Diesel engine.
Of course the choice is up to you, it is going to be your car. Only you know exactly what you want and expect from a vehicle your going to buy. And there are a lot of vehicles to choose from. Make sure you research the car or cars you have in mind. Make sure it fits your needs. Go to several dealers and test drive your choices, take them on a long test drive to get the feel of the car your driving. After a few drives, and a little research you will realize exactly which one you want, and before you know it, you'll be driving home in your new diesel or gasoline powered engine.