It might help if we knew what type of genre you are aiming for. Then we're able to make more informed critiques.
Unless you're trying to decide if it's giving the correct genre-vibe... in which case I would guess dark, maybe love-based stories? Or poems, based on the first image.
My personal preference is the dead body, though I'm not sure who well it would transfer into an ebook without being able to see the whole form on the cover. I like the border on the first (though I would consider bringing the title down a bit more). So... maybe a combination of the first two?
But I'm not sure what the genre dictates, so I'm not sure which one would work best for attracting your audience. There is definitely a dark, quirky vibe to the art style, which is growing on me the more I look at it.
The tubes wrapping the flowers don't look right. If the book will be called Poetry Written in Bone then I'd like more bone than just the severed finger with all the flesh still on it. I guess that leaves the body. I'd prefer a pile of bones with a rose on it.
I rather like the color scheme of the first one. Incorporating the dead body into the lower portion of the first would work better - and the white frame border changed into a bone border would set it off nicely.