Though, I think Hillary is as good, if not better, than all the other candidates from the perspective of intellect, temperament, experience, etc, I don't think she will get the nomination. And, for pretty much the same reason, I don't think Obama will either. And, if nominated, I don't think either will be elected.
We all prattle about how open-minded and fair we are, but when the curtain closes on the booth, there are a LOT of people out there--both Democrat and Republican--who will not vote for a woman or a minority for President. They can mouth all the want about Bill (and why didn't she leave him--though if you asked them the same question they would tell you the answer is none of your business) and the Health care debacle (much bigger than this Iraq mess, don't you know), and how Obama doesn't really have the experience (as if Bush had done a lick of work in his life). BUT...the reality is that she is a woman and he is an African-American.
I prefer Hillary or Obama, and I like John Edwards a lot. There is a reason, however, that he has been campaigning as hard as he has for the past 3 years and he is still in 3rd place. He is not connecting with the voters (as they say) for some reason. If he does not connect with dyed-in-the-wool Democrats, he wouldn't have chance in the main event.
All that being said, I think one of those 3 will be the Vice-Presidential candidate. At this point, I haven't a clue who the Presidential nominee will be, but if he/she is smart their pick will be Hillary, Obama, or John for the V-P slot.