I have no idea if this is supposed to be a funny question or not, but I like it a great deal. There's something about this that wreaks of somebody laughing at their laptop as they write it, getting a joke that only they're in on.
From what I can recall, hotdogs are pretty much made up of two parts. The bun and the wiener. Obviously, one can't exists without the other, not without being called something other than 'hot dog' so I don't think that's what this question is asking. I mean, the answer can't be 'bread is the best part'. That's dumb.
So I'm thinking there's something inside the hotdog that should be addressed. Like chicken lips or pork anus or beef nads. Hard to say which is the best, though, because they come together so perfectly to make a tasty, solid tube.
I'm going to go a little outside the bun, and talk about the experience of hot dog eating. You see, I really like to eat raw hot dogs. It's been a thing of mine since I was little. Apparently some can make you sick, and I don't care; that's how much I dig it. When I cook hotdogs, I like to put all kinds of shit on them, including onions and cheese. Sometimes I fry my hotdogs with bacon wrapped around them. But still, the raw dog is my favorite.
Raw dog. Ha.
Short Answer: Does a hot dog count as a sandwich? How do you like questions?!?