'Warrior' is Kesha's weakest, but it is still a fantastic album + one of the best albums of 2012.
'One Of The Boys' is Katy's weakest (disregarding Katy Hudson), but again it's still a fantastic album + one of the best albums of 2008.
'ARTPOP' is Gaga's weakest, and it is only an average album on the whole... only about 2/3 of the album is at / above average.