That would depend on your budget and what you are willing to spend. $1,000. is a big difference. I have in the past spend the extra $1,000. to be on a Royal ship versus another line. For me $1,000 more is worth it for the Oasis.
Either cruise they are both brand new ships. 8)
Since they are both doing the same ports I would suggest to take a look at both ship deck plans/layouts and make +/- notes on each ship.
Enjoy whichever you choose!