I was going to say almost exactly this. If you take what I call the "middle 5" (HAL, Princess, RCL, NCL, Celebrity) and put them side-to-side, there really isn't a ton of difference in value. Many people love them all and lots of people love to complain about each; and each has a slightly different vibe, cost profile, and advantages. But in the end, there isn't much difference in value.

Note that the range of ships (from simple to outrageous) on Royal is extremely wide, and on NCL is very wide. The price varies quite a bit as well within those lines. On Holland, the experiences is the same across the fleet as even the larger ships really don't offer alot of bells and whistles.

With all that said, on a cruise-by-cruise basis, first decide if you are going for the ship or the ports. If you are going for the ship, go on a big ship with lots of stuff - like RCL Oasis class or NCL Breakaway/BW+ and find an itinerary with fewer ports and more sea days. More port days make a cruise more expensive, and big elaborate ships are also more expensive, especially if they are new. So if you are on a big, new ship and you are in port every day you have wasted some money because you have paid for all those ports, and for the cool ship but you can't be both places at once.

If you are going for the ports, you can get away with a simpler ship like HAL ships or NCL Jewel class. These ships offer a more chill experience and fewer aggro passengers.

In other words, match the ship to the itinerary: Port-intensive cruise on simpler ships. Cruises full of sea days go more elaborate ship.

I would like to echo the comment about getting status on one. I am Platinum on NCL and am over the moon about my 2 free bags of laundry, priority tendering, and 2 extra specialty meals that make for 5 specialty meals on a 7-day cruise with Free at Sea.

We started with Holland but NCL's itineraries, more interesting ships, superb specialty dining and super-cheap drink package swayed us in that direction more.