Most Helpful Guy
The second one will amplify your hair color, while the last one will amplify your skins pigment. Whatever you want to draw attention to is what you should pick.
Most Helpful Girl
I think the last dress would look the best because it will definitely compliment your skin tone. Also you can dress it up or down. Either with a cute necklace and heels or make it edgy with a leather/denim jacket or boots, sneakers, etc. the possibilities are endless in the 3rd dress :)