Should I use a shaped pad or a square pad for showing?

Hi! I am showing over the weekend (yay!) but am wondering what type of pad I should use. Shaped or square? I am doing only flat classes (i.e. English Eq., English Pleasure, and Road Hack) and am wondering what would be better for these? Lucy is a very beautiful palomino AQHA Appendix filly who is very pretty and sleek (nicknamed Cadillac, lol). I am using a black bridle and A/P saddle on her. I don't really mind what type of pad I use but am just curious as to what would look better.