I agree with Andy - very much a question of personal taste. In general, the best ones are the ones that aren't made in a factory. They are made by people who care about the quality of the food they produce.
This is the shot list. There are many others that are tasty, especially in sausages, from mortadella, to a host of dried salamis. I mean, who can say no to a good soprasetta? And we haven't even touched on French and Spanish offerings.
The best hot dogs and other sausages, including balogna, are made with pork. Just pork, no chicken and no turkey. Poultry makes sausages mushy. I buy all my sausages from Omaha Steaks because they taste just like what they are. I won't even consider buying Hebrew National (sorry, Seeing-to-Believe) because they put so many spices in them, they don't taste like hot dogs. They have to be hiding something!