I was like 7 at the time & I didn't want to be in Gryffindor or Slytherin because they seemed like the 'obvious' good/evil ones, and Hufflepuff just seemed kind of lame (also, I don't really fit any of the traits like bravery, cunning, or patience). Ravenclaw seemed cool and 'different' and my favourite colour was blue, so I just said I was Ravenclaw. Skip forward 8 years and Pottermore sorted me in to Ravenclaw too, so I guess that was that!

If you can't decide between the traits of the houses, you can always just go with the house you like more in terms of the colours, animal, common room etc (hint: living in a tower > living in a dungeon)