Wealthfront vs. Betterment: Which is the best robo-advisor?

When it comes to automated investing, two platforms have stood out from traditional brokerages: Wealthfront and Betterment. They're known as robo-advisors because of their ability to offer new investors a hands-off approach to growing their money. They'll create a custom portfolio for you based on your risk tolerance, time horizon, financial goals and more, and automatically adjust your investments over time to ensure that you're on track to meet your objectives.

Below, CNBC Select walks you through a comparison of investment platforms, so you can choose the one that makes the most sense for you.

Wealthfront invests in low-cost, diversified index funds, more specifically ETFs. Its diversified portfolios include stocks, bonds, real estate and ESGs. There are three main "types" of portfolios you can invest in through Wealthfront and the allocations of each can be tailored to you: The "Classic" portfolio (which has a mix of diversified index funds), the "Socially Responsible" portfolio and the "Direct Indexing" portfolio.

The Socially Responsible portfolio is curated with sustainability, diversity and equity in mind. The Direct Indexing portfolio is meant for accounts with a balance of over $100,000.

You can't buy and sell individual stocks on Wealthfront — you can only invest in portfolios with assets curated by Wealthfront's professionals and investment algorithm. However, you do have the ability to customize your portfolio a bit and adjust the mix of assets — but Wealthfront will let you know if your choices are out of line with your risk tolerance. According to Wealthfront's website, the platform offers 239 different investments, 17 asset classes and two cryptocurrency trusts.

Betterment also gives users the ability to invest in ETFs, but more advanced investors, however, have the option to customize through Betterment's flexible portfolios. The flexible portfolios allow you to modify the individual asset class allocations in the Betterment portfolio strategy to best fit your preferences, though, you cannot pick which specific ETFs you want to invest in.

Users of both platforms can invest their money through a taxable brokerage account in addition to a traditional IRA, Roth IRA and SEP IRA. However, Wealthfront also offers a 529 college savings plan and Betterment offers a 401(k) option for employers.

When you sign up for a Wealthfront account, you'll fill out a questionnaire to determine your comfort level with taking on risk. This is determined by using your age, your financial situation and your attitude toward risk. Wealthfront will then assign you a risk score that reflects your personal details and comfort level. This allows the platform to create a portfolio tailored to your needs.

Wealthfront's advanced features include tax-loss harvesting, the savings from which can help offset the advisory fee, a high-yield cash-management checking account with a debit card and a 529 college savings plan, which robo-advisors don't typically offer. Wealthfront claims that their customers get, on average, a 1.8% boost to their returns after tax-loss harvesting. You can also open up joint accounts and trust accounts.

Betterment offers a customized portfolio for you based on a set of similar questions, and has some advanced features that include automatic rebalancing, tax-saving strategies and socially responsible investing. Betterment also provides a "tax impact preview" tool that lets you see how much you might have to pay in taxes before withdrawing funds. This platform also has a premium investing feature that requires a $100,000 minimum balance.

Betterment and Wealthfront automatically reinvest your dividend earnings for you. Plus, you can also automate deposits into each platform.

The real advantage of a robo-advisor is the low advisory fees they charge in comparison to a traditional financial advisor. Over the long term the fees from a traditional advisor, which usually come in around 1% of your total portfolio, can really eat away at your investment gains.

There is a $500 minimum deposit for investment accounts at Wealthfront. The annual management advisory fee is a low 0.25% of your account balance. So, if you have $10,000 invested with Wealthfront, you'll pay just $25 a year.

Betterment's fee is the same at 0.25%, except there is no minimum deposit for investment accounts. However, as a welcome bonus, new account holders can get up to $5,000 managed for free for a year with a qualifying deposit made within 45 days of signup. 

And for Betterment's premium investing option, you get unlimited access to real-life financial advisors for an annual fee of 0.40% of your fund balance.

If you don't have enough cash invested to use the premium investing feature, you can instead opt to pay for one-time advisor consultations, which cost a fee ranging from $299 to $399.

Wealthfront and Betterment are both solid robo-advisor options. Ultimately, though, Betterment may be best for those who want to start investing but can't meet Wealthfront's $500 minimum deposit amount and who may want access to a financial advisor. Plus, new users can actually save money if they're able to capitalize on the welcome bonus of up to $5,000 managed for free for one year.

However, Wealthfront's tax-loss harvesting feature can save you lots of money come tax time, and potentially more than cover the cost of the advisory fees. Plus, the service is currently offering a $50 bonus when opening and funding your first taxable brokerage account.

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