The number of people on a ship don't cause me any concern, it's how the space/flow works on the ship. I prefer a larger ship, everything else being equal, as it invariably offers more options with regard to entertainment, food, bars, etc !
Also, newer = better (again, my opinion)... just not brand new (first couple of months). I'd rather they have completed all details of the build and give it some time for the crew to mesh.
Tom