What is the best place for a cruise ship cabin?

That depends on several things. In general it may be best to be nearest to the places you will want to go to - restaurants, lounges, theatres etc. If you have an outside cabin, consider which side may have the best views and whether your view may be obstructed, for example by lifeboats. For a long cruise in high winds, lower decks and more central locations may be slightly less likely to produce seasickness. Finally, consider the cabin types and prices!