#1 I would've liked to see the bridge in focus, rather than the tree.
#2 Although the background is blurred, and you did a good job trying out that effect, I would like to see it even more blurred. I can make out another of the same flower, and it's distracting.
#3 This one is a bit overexposed. Their faces kind of blend in with their bodies.
#4 I'd bump up the saturation a tad to give the color a WOW factor. The colors of the sky look a little weird, did you edit it?
Overall, #4 is my favorite, and #1 coming in second (probably would've been first if the bridge was in focus).