I thought the best to visit was Japan. I have never lived there only visited there. I also visited HK never really lived there. I lived in South Korea and it's fun! But from those three choices I'd have to say it's between South Korea and Japan. Japan has Hakone which to me is one of the best places in the world to visit. If you stay in the hotel the longer you stay the better the dinner will get. It's just so clean and fresh there it's awesome!! Tokyo was lovely too! 

When I lived in South Korea there was so much going on there. A lot of activities, shows to go see. I saw a drum festival when I was there they had drummers from Japan, USA, Korea and I believe Canada. 

Japan beats China in all aspects. So do Hong Kong and Korea.

None of the above  ....  mainland China is the best experience, by far!!!

always pick the place that has perfected indoor barbecuing of meat. 

I visited Korea back in December and thought Seoul was incredible. So much more going on there than there is in Beijing. Can't comment on the other too as I'm still yet to set foot there, though Japan has been on my list of places to travel for TIME.