Which is the Most Effective Book Cover for a Sci-Fi Novel?

Please scroll to the bottom of the page and click:

"Please click to leave your choice for the most effective book cover."

Tell me which book cover a reader will pull off the bookshelves or purchase on Amazon or any another online book selling platform.
[Without Boots]
This Book Cover has mystery!
[With Boots]
This version is more sinister!
Which Book Cover will make you
want to buy the book?
[Julius Thompson]