First, you have an amazing body and look awesome in the bikini you're wearing in the pic. I've always had a thing for a girl in a white bikini. It really sets off a tan and it's just so sexy. Maybe 'cause it kind of like seems she's just wearing a plain white bra and white panties (which I love).
well, you have a great body, I'm sure you look great in all of them! Go by whichever you like most, I just don't like the top of the last one with that black stripe in the middle. but maybe it changes when seeing on a girl, I don't know. anyway, I'm sure you'll rock all of them.
I've seen a lot of girls that wear bikins like number 4 and they look great in them, there is something about the colour i think. The second one is a bit classier looking though so id probably tend to lean towards it more.