Accturally speaking, if I were you, i will choose the first one, it looks so gerousious and elegant, and it make your so slim. I tink the second one show out that your waist is a littlerough, and the third one seems a little cheap. Just my own opinion. Good luck, honey!
I love them all and they're all fairly similar but different, too! Personally, I find the material in 1 a little too shiny, but I love the floatiness of 3.
It's hard to compare them precisely, because you're posed slightly differently in each pic, but I'm not sure that 2 is as flattering around the belly as the other two are (not that you have a belly, but IMO, number 2 makes it look like you have just from the way the material changes and the bodice bit comes to a bit of a point).
1 is super flattering with the belt but I am in love with the softness of the folds on the bodice in 3.
I concur with what everyone else has said, though. It has to be the one that YOU feel best in. Did you swish when you put any of them on? If not, maybe none of them is "the one", although you do look stunning in them all.
How about imagining for each one that you'd lost your opportunity to buy it. Is there any that you'd feel absolutely gutted about not getting?