Betterment is a great option if you want an automated, low-fee portfolio from the largest independent provider of digital accounts. Betterment was a pioneer in providing "set-it-and-forget-it" portfolios for a low-fee.
Consider Wealthfront if you want a low-fee automated portfolio with a user interface that's simple and easy-to-use.
Betterment
Automated
Wealthfront
Automated