We were on Harmony just before Christmas and on Liberty last summer. Although I loved them both, I felt like there is so much more to see and do on the Harmony! I highly recommend the Chef's table (although Liberty has this as well). I also loved the Abyss Slide (not a water slide but a 10 story slide on a mat) - super fun!! We also loved the 3D movies and the excellent water show (the best show on a cruise I have EVER seen!!) Grease was great on the Harmony but we saw an Eagles show on the Liberty that was AMAZING! Sounded JUST LIKE them! I would stay on Harmony unless you need a different date or itinerary. (And I highly recommend the Junior suite if you can swing it!) But since I would sail on both ships again, you really can't go wrong either way!! Good luck planning!