I just saw an interesting, even compelling, video made by Lawrence Lessig on why he thinks Barack Obama would be a better president than Hillary Clinton. The video is linked from his blog page. Note that you pretty much have to either go to the high-res version, or just read the transcript, because the small version embedded in that page is probably too small to make out the text.
I already felt that I liked Obama better, but Mr. Lessig lists some very clear reasons.