Lue Vang is my favorite male vocalist-- my all time favorite. I really like the lyrics in his songs. His songs are very original to me. I'll never get bore listening them.
Favorite female vocalist would be Tsab Mim Xyooj.
Luj Yaj would be a good singer if he writes his own music/songs instead using other people music/songs. Almost/all of his songs, the ones I liked, the good ones, are copied from Thai, Chinese, and other Hmong artists' songs music. A couple of good songs came from copy other people's work is fine, but more than 10 songs, that's not good for me.