Your question cannot be answered with the information currently available.
"More Famous" is too idiomatic to provide an adequate answer without poll data from various areas & age groups, perhaps even from different socio economic groups.
Without any data of this sort there is no way to really determine which person is more widely known to the general populace therefore any answer would really be speculation, opinion and/or conjecture from the individual who answered.
No, Justin Bieber is still very famous.<3
I believe Justin Bieber is more famous.
Justin Bieber.
Justin Bieber, he has more fans.
Sadly, Justin Bieber.
Barney
Justin Bieber is more famous
Justin Bieber will never be famous...
Personally, I don't think either of them are more famous than the other
Worldwide is definitely Chewbacca. Barney the Dinosaur is only known in the USA
Justin Bieber
Justin Bieber.
Justin Bieber.
goku
mario
justin bieber is more famous
Yes, Justin Bieber is very famous in America.