We have sailed on Azura and Celebrity including the Edge which was fabulous.
Celebrity are more expensive generally and the gratuities add up if you don’t factor them in to the overall fare, but P&O are a good value for money cruise line.
The food is much better on Celebrity but we found the entertainment much better on P&O.
We hate the dressing up part you get on P&O as you are treated as second class passengers if you do not comply, so Celebrity wins this.
All in all you pay for what you get.