This is one I've seen too many times to count. Who did it best? I would go with "The Engagement", but the way the man is positioned it almost looks like he might be touching himself. I'm sure he actually just has his hands clasped in front of him but since that got cut off, it looks awkward. Also, the title looks a little crammed into that frame. Otherwise, it's an excellent cover and the models do not look "slapped on" to the background. Next I might vote for "Redemption of a Fallen Woman" but that yellow is hideous. So I guess I will go with "The Marriage Wager", it's the third most natural looking one without the yellow or awkwardly placed man. The blue dress is well done but I'm not sure what the background is supposed to be.
By the way, if you think I have a lot of opinions about book covers, it's because I'm a photographer with some design experience so my eye is trained to have a critical eye. No offense is intended to authors or their cover designers, consider it free advertising! This is just supposed to be some fun for blog readers.