If the Ducks could only keep one who should they keep? Not who will most likely stay, but who should they make sure to hold onto. The #1 center that can be elite if he wants to be, or the former Hart Trophy winger.
Getzlaf, because he likes it there, and the #1 C is much more important than the 1st line wing. Also, given Anaheim's group of high-end wing prospects like Etem and Palmieri, it would be a lot easier for them to help make up for losing Perry than sticking Holland in as the #1 C.
Not to mention he likes it there more(I'd assume).
That said, Perry is the better player, and I'd much prefer it that he makes it to UFA(or traded as a rental) than Getzlaf, as he'd be a perfect fit for the Canucks.