I listen to a lot of J-POP songs, and I've never really taken note to who is singing the songs I listen to. In fact, most of the time, I find the lyrics just sink into the background melodies of the song itself. However, after watching Magical Girl Lyrical Nanoha: StrikerS, and noting that the OP song changed from the first half of the season to the later half, I was pleasantly surprised to discover that the performer who sings Massive Wonders also sings my other favorite song, Eternal Blaze.... Mizuki Nana. So, I wonder, do you have a favorite singer? Because it appears that I may have become a fan of Miss Mizuki's!
I have a... strange thing with autism and my ears. It's very hard for me to understand lyrics. They sound like musical instruments to me, not words. A rare few singer manages to work around this, and Crush 40 is one of them. I chalk it up to audio mixing for exceptionally clear lyrics.
That's kind of the appeal I have for J-POP. I understand some words, and get really excited when a singer uses a word that I know, but for the most part, the lyrics just fade into the music as another instrument.