Hey denny, I can tell you South Korea is great. I am studying here at a Uni. In particular, I would recommend seoul (ofc), its a great place to be in. Although, traditionally the Koreans are known for their hardware, the market for software developers is increasing here at a very promising rate. Night life is awesome. Food is great, too. Although culturally I had some problems, but as you mentioned you've been to Japan and enjoyed their culture, you won't have any problem in adjusting here. And as you might expect Koreans (chicks) are very fond of foreigners haha (if it matters to you at all?).

Hit me up if you ever plan to visit here.