Reason 1: Kerry seems like a pretty good guy.
Reason 2: Bush only helps rich people.
Reason 3: Bush makes the world safer...for rich people. Everyone else is potential cannon fodder.
Reason 4: We are at war and we should have someone who's been in a war in charge.
Reason 5: Bush seems like the more down-to-earth personality, it's true, but everything he says is either a) a lie b) wrong or c) a slogan which does not mean anything. Kerry is often guilty of c), but as far as track records go, Bush is far ahead of him on a) and b).