Many people will tell you that turkey burgers are not only healthier than regular hamburgers, but they taste just as good. While we know the latter is a filthy lie propagated by godless mongrels, it is commonly accepted that turkey is healthier than beef. Generally speaking, yes. However, the ground up garbage in chopped meat is not so cut and dry.
According to the Internet(TM), 93% lean ground beef and 93% lean ground turkey have identical amounts of fat, and the turkey has only 10 grams fewer in the calories department. Not at all worth it for the substitution of taste (although I imagine there are those of you who will argue for the fattier burger, but this is only for people that are eating lean to begin with).
The moral of the story is that when you need a hot slab of meat between your buns, go with the beef.