VACATION CONFUSION! :[ PLEASE HELP?

Hi! My brother,my mom,my dad,and I were all planning to go on a cruise ship. But, I am trying to find the best cruise ship. I have heard that the Disney Dream is the best and also other people say that the Royal Caribbean International cruise line is the best and also the Nickelodeon cruise ship. I'm confused and really need help! *If you answer Royal Caribbean International, can you please state the best cruise ship for First-Timers. Thanks*