Japan has a long, fascinating history with real artifacts from hundreds of years ago. Koreans have a lot of stuff they rebuilt post-Japanese imperialism. Japanese people take pride in their cities and culture and try to advance toward the next best thing. You could say that Japan is what Korea aspires to be, although I'd never say that to a Korean's face.
Of the two countries, however, and based entirely on my own brief experience, I prefer Korea's character. Korea is a country stuck between the past and the present. It balances the shallow and material desires of the present with traditions that come from its poor, downtrodden past.
A common question in Korean is 밥 먹었어요 (bap meogeosseoyo). Did you eat rice? or Did you eat? In the past this was a legitimate question - there simply wasn't food to eat, or at least nothing more than simple rice. This phrase is still in use today, a remnant of this country's fascinating past.
Honestly, I don't know where I'm going with this post. I liked Japan, but I like Korea better. Oh, and Japan is disgustingly expensive. And I wore a hole straight through my shoe. Next trip to Japan I will do Tokyo and then I think I'm done with Japan.