My ALL TIME favorite Korean boyband is BIG BANG!! I really love their music and beats :)
And not to mention TOP and Gdragon are HOT!
I also listen to Japanese music and I really like L'Arc~en~Ciel! I went to one of their concerts and they were amazing! For 40 year olds the lead singer is really good looking ^^
My favorite korean boybands have to be Shinee, BigBang, Nell and U-KISS is the best. I have so many groups I like but this are what I listen to the most.