Which Tablet is the best for Reading Books Electroniclly?

I was wondering what tablets are good for reading e-books and other electronic media. I have no preference to the operating system. I would like the screen size to be over 9 inches and it has to have at least a SD card slot and Wifi. I know their are several models that are out their like the Ipad, Motorola Xoom, Samsung Galaxy tab, and the upcoming Toshiba Thrive tablet. Does anybody have any recommendations based off experience and reliable knowledge? Thanks.