I'll give you a basic review since I didn't get to use the FXP prestige for more then 2 days but had the O3 tour for a few months.
FXP Prestige felt more solid to me, it also felt more head heavy even though they have the same balance. It also can't produce spin as good as the O3 tour. It is a great baseline racquet to just hit the corners cross court.
O3 tour is a beast when it comes to spin, but you can also flatten out shots for the big winner. I was able to have long ralleys just because of the amount of spin I could put on the ball with it. One place where I liked the O3 tour more was at the net, it is a great volley racquet. Never got to serve with the prestige. Do you want a spinny racquet or do you want a racquet that has a denser string pattern and you will hit flatter with?