I just hate these lists because it is impossible to quantify which books are "most" anything. I mean don't we need to go back to at least to the era of H.G. Wells? What about The Sherlock Homes books which could be considered somewhat of an Detective/Mystery SF of their era. Every era of SF is built in the shoulders of those before them. And it's just not reasonable to say anything other than these books are excellent to read because I liked them a lot. I don't see any way to say which is "the best".
I know, I'm no fun...