Rae Sremmund, Kero Kero Bonito, Ariana Grande, School of Seven Bells, Tegan and Sara, and Yeasayer are like, the only artists who have improved from their last release than I can think of
Maybe there are more but I'm not counting artists who went from like a 3 to a 4 or a 5 to a 5.5 or whatever.
PJ Harvey
Sleigh bells
Roisin Murphy
Chairlift
Radiohead
Gwen Stefani
M.I.A. (!!!!!!)
M83
Perfume
Shinee
Solange
Tinashe
sooooo many disapointments.