Split the difference,
you can have both.

The Advantage to a ROTH 401k is that you can roll it into a Roth IRA and RMD's are no longer required.

The Advantage to a Traditional 401k is that taxes are deferred until you begin taking RMDs. The downside to RMDs is that as you age they increase, so it's pretty easy to wind up in a higher tax bracket than you'd expect.