I have also sailed on Oriana to the Canaries this year - we had Norovirus on the way home from Madeira!
Also went on Oceana a few months ago and have been on Arcadia a few times as well in past few years.
My fav in order are Arcadia, Oceana and then Oriana. We never saw a cheese board at dinner on Oriana, very strange. The food on Oceana was as good as any other ship in the fleet when I was on her in September this year...
P&O Arcadia -Canaries, Aurora- Bruges, Arcadia -Med, Aurora Amsterdam, -Arcadia -Venice, and Ventura Bruges. In 2009 - Oriana and Oceana Fjords.