Of these 3 individuals, who would you say would make the best president:  Justin Bieber, Brittney Spears, or donald trump?

Bieber.  As useless as he is (& that's a LOT), he'd bring at least a trace of the famous Canadian diplomacy & reason to the job, which clearly hasn't had any since the criminal, serial-lying fat dotard Orange Fraud too office.     

Nine of the above.

Sonny Barger would be a better prez. 

Even if Justin Bieber was a naturalized citizen he would still be disqualified.  You have to be a NATURAL BORN citizen, 35 years old, and live inside the US for 14 year.  This is the reason we don't have a President Schwarzenegger.  Your other two candidates are disqualified due to insanity

A steaming pile of dog $hit would make a better president than Donald Trump.

If this ever happened for the first time in my life I would abstain from voting. 

Bieber is not US born, so he is not constitutionally qualified for the presidency.  The other two are mentally ill.