One might chose to discount Josephus.
But then, there is Tacitus, who says:
"But not all the relief that could come from man, not all the bounties that the prince could bestow, nor all the atonements which could be presented to the gods, availed to relieve Nero from the infamy of being believed to have ordered the conflagration, the fire of Rome. Hence to suppress the rumor, he falsely charged with the guilt, and punished Christians, who were hated for their enormities. Christus, the founder of the name, was put to death by Pontius Pilate, procurator of Judea in the reign of Tiberius: but the pernicious superstition, repressed for a time broke out again, not only through Judea, where the mischief originated, but through the city of Rome also, where all things hideous and shameful from every part of the world find their center and become popular. Accordingly, an arrest was first made of all who pleaded guilty; then, upon their information, an immense multitude was convicted, not so much of the crime of firing the city, as of hatred against mankind."
Tacitus, ANNALS
He was a Roman historian who had no agenda except to document what had happened.
There are also a number of apocryphal gospels that provide much evidence.
The argument against Josephus is that there are no copies of his work that actually date from the pre-Christian period. All of them are copies of copies of copies, most likely done in monasteries by scribes not above slipping in a little extra something. I'm not really a scholar of these things, but apparently the evidence is that the passage in question has certain characteristics that point to it being written by a different author than the rest of the book.
If you're interested, here's a website dedicated to the argument over the reliability of Josephus:
http://www.earlychristianwritings.com/josephus.html