On the subject of bias.
Yes, to Alizée fans, Alizée is the "best" singer, it is a very untamed word, but that is a biased opinion. If you were to look at it technically, she's not the best, she's good live but hasn't been the best, she hasn't been the best communicator, etc.
Of course to fans this won't mean shit, she's still the best because she makes them happy and whatnot, with whatever, a string perhaps.
To others it seems different.
To others Alizée could be a good singer, to others she could be a bad singer, but their opinion on the best singer is biased towards THEIR favorite, it's a game of Suits people.
Non-Fans or semi-fans however can sometimes offer the best advice towards a star, and point out the flaws, for the fans of any will always be blinded when it comes to their favorite, trust me, I know.
The idea of "What makes a best singer" is also biased.
Some people say "If they like it then they're the best", which is narcissistic, ego-maniacal, yet still an opinion and a bias.
Some people say "If it has great musical qualities and technicalities they're the best", that's judging a piece of music based on how much work and complexity it has.
Some people say "If they can hold a great concert live they're the best", which is basing the rank of a performer based on how well they do without any studiomasking.
Jung is right on several accounts.
Of course, I may come off a little biased, we are brothers in arms.