Been on 25 Princess and 1 Celebrity (Infinity) last year and Princess pizza has always been excellent to us, and the pizza on Infinity was frozen pizza quality.
With that said, we enjoyed Infinity and are doing equinox in October to try a newer and bigger ship than Infinity. Service was a bit better on Celebrity overall, but Princess rooms and TV options are better to us, but we have only sailed on the oldest Celebrity ship.
Princess is by and large cheaper as well. But that gap is closing