Apparently, none! I was on a couple Carnival cruises many, many years ago and then returned to cruising on Viking (talk about being raptured), and the level of comfort and relaxation I've felt on my four VO cruises makes me leery to try anything else. Also, I like to have my own cabin or travel solo, which adds to the cost. So my reasoning is, if I'm going to spend so much, I want to be sure I'm happy with my choice. I will say, I've been checking out the Oceania board based on comments from people here and while the consensus seems to be the food is better, I find after about three days onboard, I'm over the food, so that wouldn't be a deciding factor for me.