Aw, exciting ng May 6 scan mo! From what I understand, 3D gives you that clear still image ng baby's face in three dimensions kaya nakikita mo talaga kung parang sino, 4D is basically 3D but with movement so nakikita mo live yung baby moving around, and 5D is like 4D pero mas HD pa ang quality ng image, mas clear ang details. A few of us tried 3D lang kasi mas practical ang bili, pero honestly kung gustong-gusto ng hubby makita ang baby moving in real time, sulit na sulit ang 4D! Either way, you'll be amazed regardless of which one you pick, congrats sa baby!