What Should I Wear II

This weekend Im going to my boyfriend's Grand Dads 90th Birthday party. Which dress do you prefer?

I like the white lace H&M dress better but I will most likely have to put a cardi over it which kinda ruins the best bit of the dress. Its hard to tell in the picture but the front of the dress cuts higher towards the center instead of dipping down into a sweetheart neckline or a straight cut across. It makes the dress feel really unique and well structured.

This second option is from the Rodarte for Target line. I probably won't have to wear something over since it isn't strapless.

Any opinions?