My wife and I just returned from an 8 day cruise on Carnival's Conquest - a 3,000 passenger ship built in 2002. That was our sixth cruise in 13 years - two other on Carnival (in the 2000's) and three on Norwegian Lines ("NCL") the past three years. We always get a balcony cabin. Here are my comparisons:
1. Cabin - Big edge to NCL
Carnival has better storage but NCL cabin is larger and better arranged with couch by the window instead of the bed. Balcony much larger on NCL and Carnival Conquest rain gutter was rusty. NCL Bath larger but Carnival shower more user-friendly and Carnival bath had six shelves. TV shelf on Carnival too large and is safety issue - protrudes and I bumped my head lightly many times. No usable electric outlet on Carnival bath and blow comb in drawer has a short cord - so one needs to bend over to use it. Two amenities missing on carnival but present on NCL - an ice bucket and a coffee machine. Really missed those on Carnival.