The absolute best and most complete biography of Abraham Lincoln is
Abraham Lincoln: A Life (2009) by Michael Burlingame and published by Johns Hopkins University Press. It is available in both print and ebook. Unfortunately, it is expensive, but there is quite a bit to it. I bought the hardcover (2-volume; list price $125) set when it was first released and having read all 2000+ pages, I can say it is a fantastic insight into Lincoln.
It does not appear to be available at Google Books.