We sailed on the Jade out of Athens in October. It was a nice older ship with great crew. The included food was pretty decent and the food in the specialty restaurants was great. If you do the air promo, make sure you ask for a deviation to arrive at least 1 day early. Otherwise, you arrive the day of the sailing and it could be dicey.
We had looked at Celebrity when booking but it was more money at the time. Ironically, we are taking the same Celebrity ship- the Apex in the Caribbean in Feb 2024. For me in the Caribbean, the ship is more important. In the Mediterranean, the ports are more important than the ship. Celebrity should be rolling out their 2024 itineraries probably next month. You could always wait to comparison shop.