With major stock market benchmarks up over 20% in 2019, there isn't much challenge for investors in finding robust sales growth these days. The harder part is identifying which of these successful companies has sustainable competitive advantages that can power impressive long-term shareholder returns.

With that goal in mind, let's take a look at a few companies that savvy investors will like for reasons that go well beyond just sales gains.

Winning market share

Consumer tech is a famously brutal industry, but Garmin (NYSE:GRMN) appears to have what it takes to win in this market. The GPS device specialist has overcome steady declines in its prior core segment of in-dash automotive navigators to post sales growth, earnings gains, and record profit margins in each of the last three fiscal years.

A hiker looks at her smartwatch GPS screen.

Image source: Getty Images.

One reason for that success is Garmin's strength in developing and marketing hit products ranging from smartwatches to fitness trackers to bike navigation equipment. The company also dominates attractive niches like aviation and has recently pushed deeper into the marine navigation segment. Theses initiatives have created a wider selling base than peers like Fitbit, while having other positive impacts on its financials, including by lifting operating profit margin.

Garmin is predicting another strong holiday season to close out a fourth consecutive record fiscal year. But smart investors are just as excited about the company's rising efficiency, broad-based growth, and improving cash flow rates heading into 2020.

Boosting profitability

lululemon athletica (NASDAQ:LULU) is benefiting from the same positive industry trends that are lifting most rivals in the athleisure market. But a few factors make the yoga-inspired apparel specialist really stand out from its peers.

Start with profit margin, which has improved by over 7 percentage points since 2015 thanks to a combination of innovative product releases and a stellar direct-to-consumer business that even Nike might envy. Lululemon's last earnings report showed off the power of that selling model, as operating income jumped 25% to $168 million, or 19% of sales.

Investors interested in this business might be more optimistic about its long-term growth outlook that includes pushing into new product categories like outerwear, entering new international markets, and building loyalty among demographics beyond the retailer's core female focus. Those ambitions look more achievable with every passing quarter of surprisingly strong sales growth.

Returning cash to shareholders

It's no secret that Home Depot (NYSE:HD) has been winning more than its fair share of the expanding home improvement industry for the better part of a decade. That success has delivered head-turning sales growth, industry-leading profitability, and robust cash flow.

A less well-known characteristic of this retailer's business is its impressive capital efficiency. Home Depot's return on invested capital is above 40%, which not only trounces rival Lowe's 14% but makes it one of the most efficient businesses in the entire market. In recent years, management has supported that killer metric through a mixture of aggressive stock repurchase spending, store upgrades, and e-commerce outlays. Those achievements should help support better financial returns for shareholders, including via higher dividend payments, even though CEO Craig Menear and his team see growth slowing in late 2019 and into early 2020.

In some ways, booming markets can make it harder to identify winning stocks because sales growth is easier to come by. But by focusing on additional metrics like cash flow, market share, and capital efficiency, investors can increase their chances to pick companies like those listed above that have durable competitive advantages.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.