One of the best praises you can bestow on a business is to call it a cash cow. Like the dairy animal that provides milk on a regular basis, a business that's a cash cow generates steady cash flow over time. Cash cows can often be excellent investment choices. Companies that consistently produce cash flow have plenty of money to reinvest to fuel more growth or to reward shareholders through dividends and/or stock buybacks.

There are several stocks of companies that are bona fide cash cows. Some are better picks for long-term investors than others. Here are three top stocks that are cash cows that you can buy right now.

Cash stuck on a cutout shaped like a cow with the words "CA$H COW"

Image source: Getty Images.

1. Apple

Few companies are even in the same league as Apple (NASDAQ:AAPL) when it comes to cash cow status. The tech giant generated free cash flow of nearly $59 billion in 2019. Apple's cash position totaled $94 billion, including cash, cash equivalents, and marketable securities, as of March 28, 2020. In addition, the company had another $98.9 billion in marketable securities listed as a noncurrent asset

Apple's iPhone products contribute roughly half of the company's total revenue. The company's regular launches of new iPhone versions keep the money flowing in on a regular basis. While iPhone sales have declined recently, the introduction of 5G-enabled versions could rejuvenate the product line.

In the meantime, services have become increasingly important to Apple and now make up nearly 23% of total sales. The company's services revenue includes its App store, AppleCare, Apple Music, AppleTV streaming services, and iCloud services.

Apple routinely uses its strong financial position to buy back shares, spending around $18.5 billion in Q1 on stock buybacks. It also offers a dividend that currently yields a little under 1%. 

2. Berkshire Hathaway

It's hard not to be wowed by Berkshire Hathaway's (NYSE:BRK.A) (NYSE:BRK.B) cash stockpile of $137.3 billion at the end of March. Berkshire produced free cash flow of $22.7 billion last year. That level seems likely to slide somewhat in 2020, though, due to the COVID-19 pandemic.

Still, though, Berkshire will continue to be a big-time cash cow. Warren Buffett's giant conglomerate rakes in steady revenue from its various insurance businesses. It also can rely on dependable revenue streams from its utilities, including electric distribution and natural gas pipeline businesses. 

Berkshire is as known for its investments as it is the companies that it operates. If you wonder whether or not Buffett himself likes cash cows, consider this: Berkshire's position in Apple comprises over 40% of the company's total portfolio.

Despite having an enormous amount of cash, Berkshire still doesn't pay a dividend. However, the company has put its cash to use buying back its own shares to the tune of $1.7 billion in the first quarter. When valuations of stocks become attractive enough, you can bet that Buffett will use more of its cash to scoop up shares of companies with solid growth prospects.

3. UnitedHealth Group

The healthcare sector represents nearly one-fifth of U.S. economic output. UnitedHealth Group (NYSE:UNH) stands out as one of the biggest cash cows in healthcare. The company generated $16.4 billion in free cash flow in 2019. Its cash position totaled $24.4 billion as of March 31, 2020. 

Nearly 79% of UnitedHealth Group's revenue stems from health insurance premiums. Should presumptive Democratic presidential nominee Joe Biden win in November, the company could have more opportunities for growth with its health insurance business. Biden's healthcare plans include creating a public health insurance plan along the lines of Medicare. Close to 28% of UnitedHealth Group's total revenue comes from its Medicare programs.

While health insurance premiums help make UnitedHealth Group a cash cow, the company's Optum businesses boast higher profit margins. These businesses include OptumRx pharmacy benefits management unit, OptumHealth health information technology and services unit, and OptumInsight healthcare consulting firm. 

UnitedHealth Group uses some of its cash to pay a dividend, which currently yields nearly 1.7%. It also regularly repurchases shares, buying back $1.7 billion in stock in the first quarter.