Which cruise line is better for a single man in his late 20s, Royal Caribbean or Carnival?

I am planning on taking a vacation/holiday in late December. I have never been on a cruise before and am considering one of two cruises. One is on Royal Caribbean's Liberty of the Seas(a Freedom class vessel) and the other is on Carnival's Triumph(a Triumph class vessel). As stated before I am single and in my late 20s, so I am looking at singles cruises. Any information you can give on the cruise lines and these ships in particular would be most helpful in making my decision, and would be greatly appreciated.
Additional Details
Just to be clear, this is a WINTER cruise, and I am also looking at activities for my downtime and also general age groups. I kinda am looking for the possibility of meeting a woman 18-36, though my primary reason is as a de-stresser and I want to make sure I have a group of people, or maybe just one person, to hang out with. That is why I chose a singles cruise instead of booking through the cruise line itself(which would have been less expensive but also less enjoyable).