It depends on your current marginal tax rate (fed + state).If you have a low marginal tax rate, it may be better to pay current taxes and be able to withdraw from the Roth 401k with no taxes due later, when you can be facing higher tax rates.For a high proportion of people though, the regular 401k that is pretax is the way to go. Esp those that currently have high state/local taxes they can avoid altogether by contributing to a regular 401k and retiring in areas with little/no state/local taxes.