That IS a tough one. To me, the Civic is a much better looking vehicle. When I bought my '06 Accord, I had actually headed to the dealer that morning to purchase a Civic, but they wouldn't discount them ONE PENNY. I had lived with my Regal for 7 years and it was time for something new. The three main reasons I wanted a Civic - 1) I wanted my first Honda, 2) The exterior styling, and 3) The digital dash. I ended up buying the Accord and got one of three things I wanted. Ultimately, the Accord just wasn't for me. I should have left the dealer and re-thought the situation. Me and the Ridgeline are very happily married now, but I didn't even consider one a year ago, since I couldn't afford it at the time.
The Civic gets my vote in this situation. Fuel economy will be better due to its lower weight and smaller displacement engine. Also, the styling of the Civic is still fairly fresh. A year from now after the '08 Accords are common and we all get used to the styling, the '07 Accord may very well look and feel dated. Fortunately, most Honda designs tend to age well, but there's always that internal thought bubble that says, "I'm driving a car with styling from 2002".