neither of them had good arguments in my opinion.
kerry mostly talked about how bush's war on terrorism is just making a big mess and how irrelevant Iraq was to the war,
and bush talked about how a steadfast, strong approach to the war without faltering off course would help keep the U.S. safe.
Kerry was very vague in what his intentions were, and did not have a solid approach.
At one point in the debate Bush made the mistake of saying, "After 9/11 we had to go after the enemy, which was Iraq". Kerry caught him on this mistake and made him look like a fool.
At another point in the debate Bush caught Kerry on his contradictory view on the war in Iraq, his view was that our troops were pretty much fighting for nothing, but then that we need more troops in the war.