Which neckline looks better?

I think i prefer the option on the left

I prefer the mesh on the left. The lace on the right takes all of your attention, I feel like I'm focusing on that piece of lace instead of the dress as a whole.

Left because it will allow the whole dress to shine The right blends with the lace better but becomes focal point because of the contrast with your skin. and the shape of the beautiful neckline kind of disappears.

I tended to lean toward no modesty panel as well, but if it is a must then I totally agree with Chrysta that moving a bit lower would still help hold it together without being quite a visible.

The right is so unique!

Oooh! It's really cool how they were able to extend the detailed pattern across the middle, but I wonder if that will actually obscure your dress's neckline in photos... can you take more pictures from about 10 feet away? I wonder if it would create different visual lines or make your dress look like it has more a square neckline.

Because of that I'd go with the simple filler on the left to give you some additional comfort and security without drawing attention!