On the left is the famous American cover. I like the image of the schoolgirl on the swings looking introspective, and the wooden planks are a nice addition. You can also tell from the cover that it's a serious contemporary cover. A bit bland, but topical.
In the middle is the UK version. I like the font of the title, and what the tag says, but the actual image makes it look like a book from the 80s and doesn't give any hint as to what the story's about.
The German cover is on the right, and while I like it, it seems better suited to a bloody thriller than a thoughtful contemporary. The green tick marks are pretty cool, though.
The Hungarian cover (left) is pretty cool. I like the image of the girl reaching for what look like bubbles and the symbolism behind it. The concept is awesome, and the more I look at it, the more I like it.
The lovely one in the middle is the Dutch version. I feel like the broken image and the paper strips really set the tone for the story, and this would definitely attract my attention.
On the right is the Italian cover, and while I love the thriller-esque feel of it, with the red-slashed 13 and the creepy face, that's also where the problem lies. It's too... "dangerous" for a contemporary novel and makes it seem like another story altogether.
The Lithuanian cover seems more like a fun, breezy contemporary than anything else, with the font and smiling girl bending over backwards. It wouldn't really grab my attention either way.
In the middle, the Estonian cover is the kind that wouldn't grab my attention very much and that I only appreciate after looking at it for a while. The symbolism of the blue leaf is neat, but I don't like this overall that much.
Finally, in sharp contrast to the others, the Polish edition (right) looks more like a night-time adventure novel or something. It would do a good job of attracting male readers instead of a largely female audience, but it doesn't convey the right idea of the story.
Overall, my favorite is the Dutch version, followed by the Hungarian and then the American. What do you think? Also, any suggestions for what covers I should compare next?