It depends. Some people draw the line at the 15% bracket - in the 15% or lower, go Roth, 25% or higher, go traditional. Appears you are in the 15% bracket.
If you see your spending going higher (outpacing inflation) over the years, then likely Roth will work out better in the long term. If you are really committed to keeping expenses down, your withdrawal phase might involve paying 0 taxes (
http://www.gocurrycracker.com/never-pay-taxes-again/), then traditional looks pretty good.
If you expect your income to rise a great deal, you might go traditional now, as later you might not be able to deduct the contributions.
If you already have a ton of traditional money, you might go Roth as you've already "filled up" a lot of the lower tax-brackets when you withdraw with existing funds.
So a lot to consider. The good news is, even if you "pick wrong" (which you won't know for sure for many years), you're still way ahead of most just by having the money invested.