Having your hair down shadows your face quite a bit and there's no wow factor or styling about the hair when it's down, makes your face appear longer. it's just quite flat. You have good facial features and your face suits the hair up style in my opinion, very complimentary.
I think wearing your hair down would look better if you teased your hair a little bit just to give it some volume on top. If you don't wanna bother then you should wear your hair up, I think that look really brings out your features.