What is the best longer cruise you've gone on?

My husband and I are nearing retirement and we love to cruise. We've done shorter cruises (3-5 days) as well as a lot of 7-8 days cruises so far when we had younger kids. As newly minted empty nesters, we recently completed our first transatlantic cruise and we loved it! I'm pretty sure that is the duration we are going for (12-15 days), at least until we retire.

I'm currently doing research for potential cruises in 2027 and there are a lot of choices. What cruises have you done that are 12-15 days long and you absolutely loved it? Please highlight what about the ship/cruise line and the ports of call you especially liked.