I’m at the highest level on Carnival, and as a solo cruiser, they don’t really have anything to offer me now. However, if the itinerary is right, and a longer cruise, I would book them. I have sailed them in Europe, twice to Australia, and in 2019, the longest cruise on their books to Singapore. Trust me, the demographic is not like an LA sailing.
I have sailed for the most part, between the 2 cruise lines, and it has never been a biggie to me when I get cruise credits, because I know I will sail again anyway.
I’m sailing next year on Celebrity on a new itinerary for me, and I do like that they reciprocate loyalty.