Sometimes, one of the best ways to learn to invest is to watch those investors who have enjoyed a tremendous level of success. However, out of all the billionaire investors in the world, which ones are the best to follow?

Source: via flickr.

We asked that exact question to three of our analysts, and here is what they had to say.

Dan Caplinger: Billionaires who earned their money by investing are great models for investors to follow, and Howard Marks of Oaktree Capital Group (NYSE:OAK) has a long and distinguished reputation for investing in areas of the market where others fear to tread. With a specialty in distressed assets, Marks often comments on opportunities in beaten-down investments with clear logic and insight.

For instance, last month, Marks wrote a note to his investors about the plunge in oil prices, using it as a lesson in how relying on predictions can be disastrous. Marks pointed out that it's hard to find people willing to make predictions that stray too far from the norm, and so hardly anyone would have predicted that, with oil at $100 per barrel just a few months ago, energy prices would fall by half in such a short time. Similarly, the almost universal belief that bond interest rates would rise in 2014 proved to be terribly wrong, as market participants were once again too impatient in anticipating much-expected rate increases.

In the end, Marks concludes that "there's little logic in investor psychology." If you can take that lesson to heart, and look for rational reasons to drive your investing decisions, your performance will be a lot stronger.

Keith Speights: David Tepper is one billionaire whose investing returns weren't spectacular in 2014. In fact, he warned in May to not "be too fricking long right now" and reduced his equity positions. The market, however, did quite well during the rest of the year.

So why should investors pay attention to Tepper? Try this: He made average annual returns of around 40% -- during a span of 20 years. If you had invested $10,000 with him in 1993, you would have had a nest egg of more than $8 million by 2013.

Tepper racked up these impressive gains in large part by focusing on heavily undervalued stocks that stood to benefit from a catalyst. He made more than $1 billion in 2009 by buying distressed banking stocks including Citigroup (NYSE:C). While Tepper's Appaloosa Management sold most of those stocks, Citigroup remains one of the fund's largest holdings. He still thinks the stock has plenty of room to run.

Not every stock Tepper buys has to be in a distressed state, though. He scooped up more than 2.5 million shares of NXP Semiconductors (NASDAQ:NXPI) last year even while the stock was on a tear. The company's prospects for strong earnings growth likely proved to be attractive.

Just because David Tepper has been successful doesn't mean investors should emulate his every move. However, success over a significant time span merits close examination. Tepper's track record keeps him near the top of the list of billionaires to watch.

Selena Maranjian: My favorite billionaire to follow is Warren Buffett, and I recommend him for a variety of reasons. For starters, of course, you might follow him by following the company he heads, Berkshire Hathaway (NYSE:BRK-A) (NYSE:BRK-B). It's one of the biggest American companies, and though insurance has been its primary focus, it's also very much a big conglomerate, owning entire companies that range from Dairy Queen to Pampered Chef to Fruit of the Loom to Benjamin Moore, and holding a multibillion-dollar portfolio of stocks, too.

I'm one of many who watch to see what Buffett or his lieutenants are buying, as that's a good way to notice some appealing companies. During the past year, for example, Berkshire added shares of Express Scripts (NASDAQ:ESRX), a major pharmacy benefit manager that you may not have heard of, but one that has seen its stock grow by 24% annually, on average, during the past 20 years. Bulls like its 10-year average annual growth rate of more than 22% for both revenue and net income, and its free cash flow of more than $4 billion annually.

There's more to follow with Warren Buffett than just his company's stock picks, though. That's because he's long been a teacher of investing, sharing many details of Berkshire's performance in his famous annual letters to shareholders, along with his philosophy and thoughts on investing issues. In his 2013 letter, for example, he discussed some of his capital-intensive subsidiaries, and how their investments will serve them well.

He also told some stories about his early investments and drew lessons from them, such as, "Games are won by players who focus on the playing field -- not by those whose eyes are glued to the scoreboard," and "Focus on the future productivity of the asset you are considering... omniscience isn't necessary; you only need to understand the actions you undertake."

Finally, we can learn from his example, as he's famous for being very selective about his investments, avoiding those outside his circle of competence, and often holding on for the very long term, through ups and downs. This rational and patient investor has a lot to teach us.