Andrew Sullivan makes the case for Barack Obama in The Atlantic Monthly. A good summary of why he's my choice, also.

Glassbooth.org asks you a series of questions and then matches you to the Presidential candidate most representative of your concerns and views. I'm no expert on politics, but I do have a few thoughts:

Most of the Democratic candidates have fairly similar policy proposals. So electability versus the putative Republican candidate matters more than any one particular policy stance.

Instead of trying to elect the candidate who will do the greatest good, it's more important to avoid electing the candidate who will do the greatest harm. I think of government as more analogous to baseball, where one superstar has less impact, than basketball, where you can build a competitive team around one great player.

I don't believe the old adage about idealistic young Democrats becoming wealthy old Republicans holds as strongly as one suspects. More likely to me that your party affiliation is set in your first couple of elections and held there by inertia and some desire for appearing consistent in your beliefs. I think Obama is best positioned to continue Democratic strength among the younger demographic, and in doing so, solidify the Democratic vote for a couple elections.

Again, I have no evidence to support these points. They are just my hypotheses.