What companies are tomorrow's big winners? In our ongoing series, I'm chatting with Fool analysts and advisors to find out the stocks they're watching. Today, Motley Fool analyst Dan Dzombak shares four companies he loves that are on his watchlist. (For your convenience, you can now create your own version at MyWatchlist.com, your free customized hub to follow the performance and Fool coverage of the companies you care about.)

Sweet returns
When he made his way through the Fool's Analyst Development Program, Dan learned many lessons about the brilliance of Warren Buffett and he sought to find companies similar to those in the Oracle's portfolio. Dan landed upon Rocky Mountain Chocolate Factory, which shared a product -- if not quite a business model -- with See's Candy. In fact, founder Frank Crail would have bought a See's franchise if they were available. Today, microcap Rocky Mountain Chocolate offers franchises and is beloved by fudge aficionados and investors alike (49 of 51 players who rated it on Motley Fool CAPS expect it to outperform the market). But as with all four of these companies, Dan's going to watch for a while -- with a P/E of higher than 15, the share price is a little rich for his taste.

Costco (Nasdaq: COST) is a bit better known, and sports a slightly larger market cap than the little chocolate maker ($29 billion vs. $58 million), but there are similarities. Costco also has a founder who remains at the helm -- Fools so respect Costco's Jim Sinegal that we've named one of our conference rooms in his honor -- as well as a strong and growing business and a smart business model. Additionally, shares of both are up a little more than 10% since the beginning of the calendar year, earning them slots on Dan's watchlist, though not his portfolio.

As much as Dan admires Costco's business, it pales in comparison to the enthusiasm he has for TransDigm (NYSE: TDG), which he describes as "one of the coolest businesses ever." The company sells airplane parts, earning modest margins on its parts that make their way into new airplanes. Ho-hum, right? But the cool part is that its margins on replacement parts are much higher, meaning the company will be earning big money over the 30 to 50 years of a plane's life. TransDigm currently trades near the top of its 52-week range, but even though shares are pricey, it's unlikely that Dan will ever stop watching, just in case.

And Dan finds the position of Philip Morris International (NYSE: PM) similarly enviable, with seven of the world's top 15 tobacco brands, including top-seller Marlboro. As he recently wrote in his review of unbeatable companies: "In 2009, the company had an estimated 26% market share in its world markets -- excluding China, where only government-owned China National Tobacco is allowed to operate, and the U.S., where the company's former parent Altria (NYSE: MO) is dominant. Its brands' images have been ingrained in people's minds through years of advertising, allowing the company to charge more for its products. Combined with an addictive product, this brand strength means Philip Morris will be a market leader for years to come." The cigarette industry certainly sees its ups and downs, so Dan's keeping an eye on this company for the next time the market decides to put it on sale.

That's exactly why it pays to watch. You can make smarter investing decisions with your own version of My Watchlist, new and free from the Fool. Click below to start following one of the stocks mentioned above:

Roger Friedman doesn't own shares of any companies mentioned, but they're all now on his watchlist. Costco is a Motley Fool Inside Value selection and a Motley Fool Stock Advisor recommendation. Philip Morris International is a Motley Fool Global Gains selection. TransDigm Group is a Motley Fool Hidden Gems recommendation. The Fool owns shares of Altria Group, Costco, and Philip Morris International. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.