For starters we have cruised on:
In order of our favorites:) Princess Royal Norweigin Costa - this cruise Carnival
Overall for the price, the cruise was great. I'm pretty easy going with food so I liked most of the food that had some European flare. I think most Americans would enjoy the food as well.
Pros Price 4 ports was awesome, even though it left a little early at some ports. Pasta was awesome! Pizza was Great despite needing more tomato sauce. Ship was clean Some of the Shows were good. Most of the food was great. Customer service was great.
Cons I'm pretty active on the ship, or at least try to be. There wasn't too much to do on sea days. No rock wall like Royal, organized sports games did not occur due to lack of participation. Some of the Europeans on the ship were rude, by American standards, by being very impatient, almost childish if you asked me lol. Decors is gaudy! Gym needs more treadmills and felt a bit small.
Given a choice I would still chose Princess, Royal, or Norwegin, over Costa, but the Price was right.