Is there a fairly comprehensive of the pros and cons of different cruise lines?
I see that you've received some anecdotal 'reviews' of preferences by TUGgers. Not pro's and con's. This might take answering some questions. As you know, timeshares differ too. So here's some observations of mine. YMMV!
First, it depends a lot on the type of cruising you want to do. Ocean or river? Pretty obvious. Do you want a small, intimate, yacht-like experience, or MEGA ship with multiple restaurants, theme park activities, and Broadway-style entertainment? Do you want the 'boat ride' to be the draw, or the ports of call? Do you want your cruise to be a family affair with activities for kids? Teens? Young adults? How about seniors? Are you OK with multiple accessibility scooters and/or walkers? Do you want to be in a balcony cabin, or to save money in an inside or 'ocean view' cabin?
We choose the cruise line by the type of cruise we are taking. For instance, in the Mediterranean, we like smaller ships- some even 'foreign flagged- smaller ships. Greek or Italian. They know the smaller ports and can get their smaller vessels into them- but don't expect the entertainment and multi restaurants on them. But on a Trans oceanic (Atlantic or Pacific) give me the BIG ship for the full service and the smooth ride and the nightly shows. In the ports, think about what a (or several 3,000 passenger) cruise ships do to the economy of a small island- or Alaskan coastal- community when they show up for a day with all those people wanting a 'genuine' experience.
Others have mentioned that Carnival is not their favorite. Here's why. They are 'party boats'. Think Spring Break. Lots of drinking and party games and the casinos rock. They have people called 'animators'. If you sit quietly, they will try to get you on your feet, dancing, or participating in the revelry. I'd had it when in the dining room, waiting for a waiter to take my dessert order, I saw him leading a conga line dancing through the dining room with many others twirling a napkin! Obviously, with Carnival being the largest cruise line and parent company of many others, some folks REALLY like them, just not me.
Anyway, OP, give an idea what type of cruising you want to do, and I'm sure you'll get opinions about what line(s) might give you the type of experience you desire.
Jim