If I’m eligible for both a traditional deductible IRA and a Roth IRA, which is a better choice?

The answer is partially dependent on your tax bracket at the time of the investment versus your tax bracket at retirement. At retirement, if you will be in a lower tax bracket, the traditional, deductible IRA is a better choice; if you will be in a higher tax bracket at retirement, then the Roth IRA is a better choice.