Reddy, so far it seems like Princess would be our favorite line. We have also sailed Carnival (5 times) and have always had a decent time. As long as you go into a cruise open minded and try not to compare it to previous cruises, there is no reason you shouldn't have a great time on any cruise. Granted, there could be issues that can strain your enjoyment but take it in stride and realize that "issues" can happen with any vacation. As for what is special with the lines I have sailed, Carnival for us is the "Party Boat" of cruises, Celebrity is a bit more laid-back and focused a bit more on the luxury of the cruise, Royal Caribbean is like Carnival without the steroids, Norwegian was (haven't sailed NCL since 1995) like Celebrity (back then). Not sure which Carnival you sailed but we were on the Celebration (retired), Ecstasy,Dream,Pride & Triumph.