Let's look at this list from a viewpoint of what Obama lacks and where these potential picks can lend a hand.
1. Executive experience. Sebelius, Kaine and Bayh all have it. Biden doesn't. Really, McCain doesn't have any executive experience either, so this is really a weak point overall for Obama. Experience in general would be helpful--Obama lacks it, but all of these people have it, so terms of balancing the scale on the expereince level, all would help Obama a little.
2. Foriegn policy weakness. Biden is the hands down champ here, with more foriegn policy experience in his little finger than Obama in his whole body. But the Biden weakness is that he is a Senator with foriegn policy experience and that really isn't going to help. Biden has been in the Senate since he was elected at age 29 (he was 30 by the time he was sworn in). Sure he is more knowledgeable, but he has never had to suffer the ignominy of a foriegn policy defeat since it is the White House that takes the blame.
3. Unrehearsed campainging. I don't really know Sebelius that well, but Kaine, Bayh and Biden are all good choices. Obama excells at the big event, scripted speech type events, but falters and stumbles when dealing with smaller, unrehearsed or interactive events, where he can't rely on prepared remarks or responses. In particular, having seen Kaine closer up, he is better at it than the others.
4. The "Gravitas" factor. One knock agaist Obama is he is something of a lightweight, he looks and sounds smart and may actually be smart, but he doesn't come across that way. A VP pick will need to add some depth to the campaign. I like Bayh and Biden for this concept.
Marc Ambinder notes:
Sebelius and Kaine are both governing choices, not campaign choices. They're not going to match Obama's enthusiasm levels; they're not going to do all that well at the VP debates; they're not even going to solve political problems (even Kaine). But they are solid; they are centrist-in-style; they are Washington outsiders; they know how to balance budgets and deal with Republicans. As an historical analogy, think Clinton's choice of Gore.Obama, assuming he wins, will want to win one more time, and unless he can successfully govern in the White House, 2012 will see his exit. Thus, I am thinking Sebelius or Kaine, with Bayh in there.
Choosing Biden or Bayh would put in the White House strong and knowledgeable legislators who would be expected to do heavy lifting with allies and adversaries. both would do well at the debates; Biden is flashy and might upstage Obama, but he'd be the best sheer campaigner and his selection would bring a jolt of enthusiasm to the Democratic ticket (as if it needed more). The downside here is the same as the upside: the focus will be on the ticket and not on Obama, per se. Bayh and Biden would call attention to Obama's manifest lack of engagement with American foreign policy. And Biden, in particular, would face a prolonged period of press recapitulation. (And could Obama trust him to keep his mouth shut?)