What is favorite cruise line ?

Each cruise line has their differences and I've been on Carnival, Princess, and Royal Caribbean.  My preference is Royal Caribbean.  I am part of their loyalty program (Crown and Anchor Society) and get some nice perks anytime I sail with them.

I've sailed with Carnival and Royal Caribbean.  Between the two, I liked Royal Caribbean the best.

Oceania and Azamara.  Both "Luxury lite."

Would not even take a FREE Carnival.  The Greyhound Bus of ocean liners

I like Titanic ship

I have cruised on Royal, Celebrity, NCL, Princess and HAL but my favorite is Royal Caribbean.  In my view Royal has the best ships and for sure the best frequent cruiser program with its Crown and Anchor Society; great benefits!!  One other thing I like about Royal is the variety of ships from ones with 2-3K passengers to ones with %k passengers, and so you can pick a ship with lots of activities vs one with lots of quiet time, like its Radiance Class ships.  I love the long open outdoor promenades on most ships and also the ships that have open access to their heliport.

You can have whichever you choose as your favorite.

Norwegian or Princess

Holland America is pricey but, it's the older senior group, no kids. Smaller ships, less people.

I've done 3 Royal Caribbean, 1 NCL, one Carnival, and 14 Celebrity.  I like Celebrity best because there are fewer kids, the food is better, it's really laid back, and I meet a lot of cool people.  My least favorite was NLC.  The food was lousy, the ship was poorly run, and I found it overall to be lacking in quality.  

Our best cruise was with Princess but everyone will have their own idea of what their favourite would be.

Bare Necessities Cruise line. But their dress code is a bit unusual.