For as much time as people dedicate to investing and saving in the years leading up to retirement, an arguably more important question looms: Which stocks should you own once you get there? To that end, we're always on the hunt for "value stocks" -- that is, stocks that trade for less than they're actually worth, so they provide investors who have a particular aversion to risk with a reasonable margin of safety. But it's easier said than done to find the best value stocks our market has to offer. So we asked three top Motley Fool investors to each pick a value stock that would be suitable to hold in retirement. Read on to learn why they chose Carnival (NYSE: CCL), Vanguard Value ETF (NYSEMKT: VTV), and Aflac (NYSE: AFL). IMAGE SOURCE: GETTY IMAGES. Cruising to market-beating gains Steve Symington (Carnival): It seems cliche to offer a cruise business as a value stock for retirement. But even with shares of Carnival up nearly 30% far in 2017 as of this writing, I think investors could still do well adding the cruise operator to their portfolios. With 10 cruise line brands hosting nearly 11.5 million guests each year, Carnival commands a staggering 50% of the global cruise market and stands tall as the world's largest leisure travel company. To be fair, Carnival's growth appears modest at first glance. Wall Street expects its revenue this year to rise "just" 5.1% to roughly $17.2 billion, while earnings per share are expected to climb around 8.4% to $3.74. But the underlying trends of that performance are most encouraging. Carnival saw a more than 5% increase in cruise ticket prices last quarter, validating its focus on guest experiences and innovative marketing and PR programs. Carnival is also benefiting this year from a delightful combination of lower fuel prices, higher spending in developed countries, and strong demand from its Asia operations -- the latter of which stands a big reason investors are so excited for Carnival's second-quarter delivery of Princess Cruises' Majestic Princess, the first ship tailored specifically for the China market. Looking forward, Carnival CEO Arnold Donald also indicated that the company is "realizing sustained strength in booking trends across all core products." Meanwhile, Carnival stock trades at a reasonable 15.5 times this year's expected earnings, offers a solid 2.4% annual dividend yield, and the company recently authorized a stock repurchase program of up to $1 billion in shares. So for investors willing to buy even after the recent rise, I think Carnival is still a bargain. This value stock fund may be the best way for retirees to go Jason Hall (Vanguard Value ETF): For retirees, it can be difficult to balance the importance of protecting capital you'll depend on for living expenses against short-term losses, while also allocating at least some of your retirement savings toward long-term growth. Considering that most people who reach age 65 will live past 80, being able to invest for both growth and stability is critical. For this reason, many retirees should consider using ETFs as well as individual stocks for growth, and one that is worth considering today is the Vanguard Value ETF. This ETF, which tracks the CRSP US Large Cap Value Index, is very low cost with an expense ratio of 0.06% (or $6 for every $10,000 invested per year), and has offered very close to market-level total (dividends included) returns over its lifetime: VTV data by YCharts. This is a great way for retirees to get adequate long-term growth with the assets they'll depend on in another 10 years. Since this fund is comprised of over 300 stocks, the risk of a single stock pick going badly is eliminated, offering solid downside protection, at the sacrifice of the upside opportunity of owning a single or a few stocks. Giving up some upside potential for much lower downside risk is a fair trade for retirees. Factor in a 2.4% dividend yield (better than many investment-grade bonds), and the Vanguard Value ETF is ideal for many retirees. Supplemental insurance for a solid retirement Chuck Saletta (Aflac): Supplemental insurance titan Aflac may be best known for its spokesduck, but its business and stock make it an intriguing candidate for a retiree's portfolio. Aflac currently trades at 12 times its anticipated earnings and is expected to increase those earnings by around 8.5% annualized over the next five years. That combination gives Aflac a reasonable shot of being a value priced stock in a market many believe to be overheated. Of course, for a company to truly be a value, it needs more than just an apparently cheap price tag. Aflac's value is backed by a strong balance sheet that includes a debt to equity ratio below 0.4 and cash-on-hand over $4 billion. That gives it flexibility to withstand a typical economic slowdown and higher than expected claims on its insurance policies, providing a decent foundation beneath that value price. In addition, Aflac is a leader in its primary industries. It's the largest supplemental insurance provider in America and the largest cancer insurance provider in Japan. That leadership position gives it scale, which is key in the probability-based business of insurance. Aflac also rewards its owners with a dividend of $0.43 per share per quarter, representing a decent 2.2% yield, while still paying out less than a third of its earnings. Aflac has also been increasing its dividend for decades, showing a long-term commitment to rewarding its owners. Put together its reasonable price, solid balance sheet, leadership position, and solid dividend, and you paint the picture of a company that truly looks like a value stock. It's that combination of solid factors that make Aflac worthy of consideration as part of a retiree's portfolio. 10 stocks we like better than AflacWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the 10 best stocks for investors to buy right now... and Aflac wasn't one of them! That's right -- they think these 10 stocks are even better buys. Click here to learn about these picks! *Stock Advisor returns as of August 1, 2017Chuck Saletta owns shares of Aflac. Jason Hall has no position in any stocks mentioned. Steve Symington has no position in any stocks mentioned. The Motley Fool recommends Aflac and Carnival. The Motley Fool has a disclosure policy.