I listen to a ton of KPop. I usually check the Korean Billboard and a couple fan made charts weekly to see what new good stuff has come out. The only JPop songs I really hear are the ones that are sung by the Korean groups who cross over for a wider appeal. I recently looked at a JPop chart and thought some of the songs sounded good, though.
You and I are like exact opposites when it comes to this.
I normally stick with the JPop and listen to Korean Songs when they cross over to the Japanese side!
Like I said though Girls Generation are pretty good and I remember when the song Let's Get Together Now first came out and it was a collaboration of the band Chemistry, Sowelu, Lena Park and Brown Eyes. And you know what? Both the Japanese and Korean version of the Song are pretty damn good!