9 Best Robo-Advisors for Consumers

As noted previously, 401(k) management from a robo-advisor is pretty rare. Blooom (with three O's) focuses exclusively on defined contribution plans, regardless of where they're held, using the investments offered within the plan's lineup. It charges between $5 and $99 a month for its services, with no account minimum.

FutureAdvisor's 401(k) advice is limited to Premium account holders, who pay a 0.50% management fee. Furthermore, Premium account holders must have accounts at Fidelity or TD Ameritrade. Those who have an account with Fidelity, and whose accounts are enabled with BrokerageLink (and have a balance of at least $10,000), don't pay any management fees to FutureAdvisor. That covers about 63% of Fidelity 401(k)s, the report found.

NerdWallet found Blooom's fees are on the high side for smaller account holders compared to other tiered fee structures. The report found the median account balance managed by Blooom is $31,300, putting it in the $19 per month fee range. That comes to a 0.73% management fee, compared to 0.50% at FutureAdvisor.

NerdWallet gave both platforms four-star ratings.

Best Robo-Advisors for Access to Financial Advisors

Personal Capital

Honorable Mention: Vanguard

Consumers who want more personalized services with occasional advice from an advisor should look into one of these providers, the report found. NerdWallet gave both Vanguard and Personal Capital four out of five stars.

Vanguard's 0.30% management fee is slightly lower – and more in line with competitors – than Personal Capital's fee range of 0.49% to 0.89%. The drawback is that the personalized service that might attract consumers to Vanguard's platform is limited to those with accounts above $500,000, despite an account minimum of $50,000. Personal Capital has a lower minimum ($25,000); even though those clients with smaller balances are paying higher fees, they have access to an advisor regardless of their balance.

Best Robo-Advisors for Free Services

Charles Schwab

Honorable Mention: WiseBanyan

While both WiseBanyan and Charles Schwab's Intelligent Portfolios platforms charge 0% management fees, NerdWallet pointed out that "very little in financial services is completely free." The investments have their own expense ratios, of course, and clients on these platforms have limited access to certain services. The report found WiseBanyan users have to pay an additional fee for tax-loss harvesting, while Schwab's platform only offers that service on accounts with more than $50,000.

NerdWallet gave Schwab Intelligent Portfolios 4.5 out of five stars, just edging out WiseBanyan's four stars.

Best Overall Robo-Advisors

Taking all things into account, NerdWallet found robo pioneers Betterment and Wealthfront to be the best overall digital advice platforms. Both offer low management fees, reasonable minimums, easy-to-use interfaces and innovative tools, according to the report.

"It takes a lot for smaller, independent companies to maintain their footing amid a slew of new launches, but Betterment and Wealthfront have managed to do that," O'Shea wrote in the report.

Both platforms offer automatic rebalancing, tax-loss harvesting and diversified portfolios, but they differ in their fee structure. Betterment charges 0.25% for its digital-only service. Wealthfront manages $10,000 for free, charging a flat 0.25% for assets above that level.

That means advisors are competing with Wealthfront and Betterment for smaller clients, particularly since Betterment's rollout on Jan. 31 of Digital Plus and Premium services. For and .40% and .50%, repectively, clients can now get varying levels of service from a human advisor.

— Related on ThinkAdvisor:

• John Hancock Uses NextCapital to Bring Robo-Advice to Its Retirement Savers
• 5 Things Top-Performing Advisors Do
• 7 Pioneers Taking Advisor Tech to New Levels: The 2016 IA 25 Slideshow