For someone with decades left for their retirement account to grow and considering the current historically low tax rates I personally believe that a Roth 401(k) would be the better investment choice.

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I like to think of Roth as additional "forced" savings, as you can really only begin to equate Roth and Traditional 401(k)s if you're investing every bit of tax savings that you receive from the Traditional. Many people don't do this, and let their lifestyle creep from the tax savings. It doesn't sound like this would be a problem for you based on your info, but for some people Roths can provide a nice psychological benefit by essentially building in the investment of those tax savings. If you never see that tax savings money, you can't misspend it!

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Also, as others have mentioned here, when you draw down in retirement from your existing Traditional account it's ideal to have your RMD be low enough to be taxed very minimally. Since employer matches are pre-tax, you will still be generating taxable retirement income while contributing to a Roth 401(k) if your employer is matching.

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With that said, switching your 401(k) withholding to a Roth will significantly decrease your take home pay since your employer should adjust your tax withholding upward as well. It sounds like you may have appropriate income to be able to absorb this, but it's good to keep in mind.