Which do you prefer? I tend to go for the "3-prongers" as I like to call them. They may look a little odd, but they're the best IMO. You don't have to push as hard to get the food stuck on it and since 3-prongers weigh less, your hand doesn't get tired as quickly. Usually if I'm out at a restaurant and they set 4-prongers out, I'll ask them if they have any 3-prongers. Usually the answer is no.
But the number one reason I like the 3-prongers more is a reduced risk of injury. With the 4-prongers you have to open your mouth wider. Also more prongs = more risk. And that's a risk I'm not willing to take.