I wanna see what colors you post but I was definitely thinking that maybe one should be foil and then the other is regular for those who can't afford it unless that's really expensive to do. For colors.... maybe orange or royal blue? *is shot* I personally like bright colors haha.
Though I still like the idea of a glow-in-the-dark t-shirt as well ;3
I don't know much about shirts so that's the best I can do... sorry.