That is a very subjective question and you will get a zillion different opinions. It is all relative to what one experiences on a particular ship at the time they sail. I have been on all the major cruise lines. When people ask me which one is the best, it is difficult to truly say one over the other. Each cruise line targets different markets. Each is known for something different. Some may say RCL is better because they like all the amenities of rock climbing wall, miniture golf, bungee jumping, or the new surf pool coming out this year. But if you don't use those amenities then another cruise line could fit your style just as well. You can't even begin to compare a Windstar cruise to RCL, CCL, NCL, or even CEL, PCL, or HAL. When it comes to food on the different lines you will get a lot of different opinions too. Maybe I'm just not a picky eater. I think the food has been great on all the lines. Yes, sometimes something may not be cooked perfect, or not as hot as it should be. But can you honestly say that has never happened in a restaurant at home? And sometimes service may have seemed slower then what you think it should be. But haven't you experienced that at home too? What I have noticed is the difference in the big production shows. Some lines the dancers come out in different costumes with every song, and the stage back drop, and stage props change to go with the song. But a couple of cruise lines I have been on I've noticed they may change costumes, but the back drop and stage props are very simple or they don't even have any.
You will have a better experience if you are on a ship matched to your needs. That's where booking with a Travel Agent will help.
The bottom line is to keep an open mind and have fun.