I prefer the cruise ship. there is nothing nicer than being in the middle of the ocean and away from land. However the other nice thing is when you see land it is a different place from the last one.
I guess it's because I spent so much time looking at water that the "sea days" out of sight of land are not that appealing to me. I really appreciated the just-completed river cruise on the Rhine and Danube, because there was always something other than water to look at. I haven't travelled all that much by train, but the train trips I have taken have been quite enjoyable. That got my vote.