My opinion, and it is only that, is that the top background image (plain) is better (it took me a while to even work out what it was you added to the second), but I like font choices of the second a little better. I'm guessing you don't like to see too much unused space on your cover
. You seem to want to fill it with text or with something, and I think that might be a mistake.
The thing I find strange is that I was going to suggest that the bright blue shadow on your previous example was too bright, but in comparison with these latest two covers that brighter shadow did lift the overall image considerably. These second two look a little dark, though perhaps that suits the mood of the story better?