I would say Carnival, but that is me. You have to ask yourself what do you want to do. RCI ships, the newer ones, will have sports mided activities like boxing, skating, rock climbing, and on the new Monster class ships a flowrider surf simulator. If you are sport minded and want to climb a rock wall, or ice skate, or box, or attend "enrichment" session then stick with RCI, but if you want fun, fun, fun and more fun, go with Carnival.
If you really want to try something, do a seven-day out of Galveston. Conquest is a wonderful ship--even though the drive from Houston to Galveston is a pain. RCI has Voyager sailing out of there for now too, and that ship has everything I mentioned above.
SO much choice, it is hard to decide!
2007 Victory & Triumph
2008 Conquest & Liberty
2009 Valor, Freedom, and Splendor
2010 Glory and Liberty
I gotta go where it's warm.....
Over 40 victim of fate.....