I would definitely max the Roth before adding more to taxable accounts. If you need the money early, you can still take out your contributions without penalty, and the earnings would likely have been small anyway (since its early) so it's a small loss to not be able to access them yet. If you can wait to withdraw it until traditional retirement, then you'll have gained all the tax savings on the earnings (which will have been larger due to the longer time).
As for the 401k - it does depend a lot on how tax rates change, but another factor is how you invest - if you trade frequently (and have options to do so in the 401k), then the tax-deferred account is almost certainly better. If you take a more passive approach like MMM (vanguard total stock market index), then taxes on the gains are less of an issue, especially since long term capital gains are taxed at 0% if you're in the 15% bracket (though that may change). If I were in the 15% tax bracket, I would contribute just enough to 401k to get matching, because I think my marginal rate won't be any better than that in retirement. If you get future raises that bring you to the 25% bracket, though, I would increase the 401k contribution so the government won't take an extra 10% of your raise.
One other thing to consider - are state taxes going to be any different in retirement? For example, I currently live in WA, which has no state income tax, but in retirement it's likely that we'll move to UT, which has 5%. This reduces the benefits of deferring taxes for us, since we'd pay 25% marginal now, and 20% (instead of 15%) in retirement.