Best covers will polarize people. Some will say it's brilliant some will say it's stupid and idiotic(esp. applicable for simple, minimalistic covers).
You haven't said what you want the cover to communicate about the story. So can't really judge it against that, but from technical standpoint and my taste 4th and 5th are the best. I'd use model from the 5th on the BG of 4th. Really like the colors and blending...
Also, you might want to have 2 or even 3 cover options and test them on Amazon, instead of asking people. Nothing is as real as results from testing. Even best intentions can misguide unintentionally. You never know until you test.