It depends on what you're interested in.

I haven't been to Nagasaki in a long time (I hope to remedy that on my next trip), but I remember it as being a great place for anyone interested in Japanese history, because it was the only port open to the outside world for nearly 250 years, with the Dutch having exclusive trading privileges, and before that, it was the headquarters for the Portuguese Jesuit missionaries. Nagasaki still has the highest perThere's also a strong Chinese influence.

It's a more visually interesting city than Hiroshima, being built on hills like San Francisco, and the people are friendlier (in the sense of being open to interactions with strangers) than in other parts of Japan.

It's atom bomb museum is not as large or as well-touristed as the one in Hiroshima, but one fascinating fact is that the hilly terrain sheltered parts of the city from severe damage. (A modern bomb, alas, would have flattened the hills).

You can take a Shinkansen to Hakata (Fukuoka's main station) and local express trains to Nagasaki. Supposedly there will eventually be a Shinkansen to Nagasaki, but I don't know when that will happen.