Majesty of the Seas - 10/03 & 02/07 & 11/08
Enchantment of the Seas - 10/04 & 10/11
Mariner of the Seas - 10/05
Vision of the Seas - 10/06 & 09/07
Carnival Liberty - 10/07
Adventure of the Seas - 9/08
Ruby Princess - 12/09
Voyager of the Seas - 9/10
Carnival Spirit - 11/10
Oasis of the Seas - 9/13
For any of those lines, it would depend on the itinerary. Any of them would be a great choice on the right itin.
Secondly it would depend on the ship. I don't like megaships. But again on the right ship any of those lines would be a great choice.
Somehow, if we really tighten it down and say "On the same size ship, and the same itinerary which would you choose?" I would have to reply that is the Aristotlean logical fallacy "hypothesis contrary to fact" and only an illogical fool would answer.
SO ... my answer is that if that is the case, HAL would have the very tiniest edge and Carnival would sink to the end of the line.
Star Princess 2005, Sun Princess 2005
Caribbean Princess 2006, MSC Lirica 2006 , NCL Pearl 2007, Majesty of the Seas 2008, Carnival Destiny 2008, MSC Lirica 2009, Carnival Valor 2009,Carnival Legend 2010, Carnival Liberty 2010,Carnival Fantsay 2011,Carnival Valor Feb 2012, MSC Poesia Dec 2012, MSC Poesia April 2013, Carnival Legend Nov 2013, MSC DIVINA Jan 2014
Well, this did actually happen to me, a travel agency called and told me I'd won a cruise in a contest, and I had to choose. Of course they tried to suggest their most expensive ones so I'd have to pay the difference, but we did our research and chose Princess, just so we could cruise with entertainer Bert Stratton again.
However, at this point in time, if Kuki called offering a free cruise, I would probably pick Holland America or Celebrity, based on positive experiences most recently.
Celebrity! A friend of mine won a 5-nighter on Carnival. She was not very enthusiastic about the experience and she had not even sailed Celebrity. She said comparing it to cruises on Princess and RCCL, well, it was not even in the ballpark.