I can't decide; there are lots of parts I enjoy.
I've always thought that "Riddles in the Dark" was effectively creepy. Then again, that was the first bit of Tolkien that I ever read as it was reprinted in our Fourth Grade Reader. This would have been around 1969.
I always liked the Out of the frying pan into the fire chapter. And of course the Battle of the Five Armies.
The dialogue with smaug
I agree with you there, maybe once I reread it again I can answer that question.