After 25 years of cruising with Celebrity, based on a lot of reviews - this cut and that cut... we tried NCL Haven and had a wonderful cruise. Food and service were impeccable, our butler was absolutely great. Suites was very specious, large bathroom, hot tub in the suite. We didn't care for Free style cruising, but otherwise amenities, that comes with Haven are better than in Retreat.
Next year we are planning to try MSC YC.