P&O (UK?) and Cunard both offer very different experiences, was there one style that you preferred over the other, if so which. It is very difficult to make a suggestion with limited information.
Also where would you want to be sailing to/from, and at what time of year as again these can make a huge differnce to the choices.
Enjoy looking, that's half the fun ;o)
Last: P&O Oceana December 2016
Next: NCL Jade August 2017
Then: P&O Ventura December 2017
Golden, Grand(2), Caribbean, Royal, Sea(4+1 aborted)
Adonia(4+2), Arcadia, Artemis(2), Aurora(5), Azura(2), Britannia, Oceana(4), Oriana(12), Ventura(2), Victoria(5)
QM2(2), QE2(9), QV(7), QE, Caronia(2),
Oceania Nautica, Minerva, Minerva II, Fred.Olsen(8), NCL Jade, =X= Eclipse, HAL Ryndam, Aza.Journey, CMV Magellan