I like the black one but that's me. Like Crankin, I wear a lot of solid black pieces and add splashes of bright colors (beads, sweaters, scarves, etc).

You could accessorize that one easier (malachite bead necklace and a bright aqua pashmina!) and I think it would be more versatile. Pair it w/a jacket or cardigan and you can wear it to work.

But this is your event so get the one you like. You'd look lovely in either dress.