Unfortunately, to be able to judge, your going to have to model both suits, because just because it looks OK on someone else, does not always look good on you, but if I had to choose, then I think it would be the black, but be warned, it might not suit you all the same, good luck,x
Given the choices it depends on your skin tone. The one that has the highest contrast with your skin tone will draw the most attention, and this is not so much a matter of sex appeal or anything as it is optical science. The only thing that could draw even more attention is bright colors.
If you want my honesty you are beautiful no matter which you pick as long as you are comfortable with that certain swimsuit on and if you comfortable with your body that's all the matters so like I said you are beautiful girl or should I say you are a beautiful young woman it don't matter which swimsuit you wear