A poll, really? Each time you base any decision on a poll on a biased sample - a statistician dies.
That said, I might provide some help in addition to being a prick.
The 2nd one is IMO better on several counts:
1 - it's more unique, the circle catches attention. There's nothing important hidden by the black block. By contrary, it catches the most detail-saturated area (what is lost? 2 peaks and some grass?). It's like with jam - spread the same amount of it on small and big loaf - which one you figure will get snatched from plate first?
2 - the second one looks too much like 4e outlay. "So what? You'd turn down a car because it drives too much like Porsche 911?" - well, "extremly good" and "recognizable and associated" are not the same.
You'd risk people looking at the book not as "system x" but rather "a system that is not 4e". Yeah, all in all it's a common layout. But currently it's used by most common system.
3 - much better details upclose. The "teared up" look from cover 1 doesn't look so well in big version (then again I dunno how close to final ver are those pdf files). The circle in C2 looks more... finished.
4 - Pure and simple, "Core Rulebook" on second cover is easier to read, it catches attention even if you just skim through books, while you have to focus to read it on the first one. Why did you use a font without sheriffs for that(especially since there's very little colour discrepancy between letters and background)?
BTW - as I listed my reasons, I realize that most problems I have with C1 could be eliminated without tossing out entire layout... But as it is, they stand.