Facebook (NASDAQ:FB) and Netflix (NASDAQ:NFLX) have been passing ships in 2019. Facebook, dogged by data privacy concerns and stubborn usage trends as recently as last year, has bounced back to become one of this year's best-performing megacap stocks. Perennial market darling Netflix has gone the other way, falling out of favor after a rough second quarter and fears of looming competition.

Both stocks have been market beaters over the long haul, but what if you could only buy one? Let's size up the two odd-numbered components of the FANG acronym to see which one deserves a place in your growth stock portfolio

Employees working at Facebook offices in Germany.

Image source: Facebook.

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Facebook and Netflix are growing their top lines at similar clips, rising 28% and 26%, respectively, in their latest quarters. Revenue also accelerated for both companies from the year-over-year gains they posted in the first quarter of this year, a rare sight, as top-line bursts typically slow as companies get deeper into their growth cycles. 

The big difference right now -- and the reason Facebook is beating the market with its 36% year-to-date return, with Netflix clinging to a 9% gain -- is living up to expectations. Fears that we were hitting peak Facebook when younger stateside users started hopping on other platforms haven't played out. User growth has risen 8% over the past year to hit a whopping 2.41 billion monthly active users. Netflix, on the other hand, fell short of the revenue and subscriber targets it was forecasting for its latest quarter. 

Looking ahead, Facebook's future is still cloudy with so many rising social media platforms out there. The fear is a bit more tangible for Netflix, as we know at least one major competitor will be launching in less than three months. 

When it comes to valuation, the two consumer icons are surprisingly similar with their top-line multiples. Facebook and Netflix command enterprise values that trade at 7.4 and 7.7 times trailing revenue, respectively. At the other end of the income statement, it shouldn't be a surprise to see Facebook stepping up as the better bargain, given Netflix's percolating overhead as it ramps up its content catalog and international expansion. Facebook is trading at 28 times this year's expected earnings and just 19 times next year's target. 

Netflix is growing its profitability even faster, but it's trading at far higher income multiples. Netflix is fetching a beefy 89 times this year's analyst earnings estimate and 52 times next year's forecast.

Facebook seems to be winning every battle, but let's close with the moat war. Which company has the more defensible platform against the inevitable competition? Both companies are better protected than you probably think. Sure, you may know a lot of people who have quit Facebook. It's also painlessly easy to not renew Netflix. Both dot-com giants are still stronger positioned than you think to win you back.

Facebook, after all, has 2.41 billion monthly active users -- more than half of the world's estimated 4 billion people with internet access. Those connections make Facebook difficult to let go. Netflix has the benefit of 151.6 million paying members, and that's a lot of people to spread content budgets across. There are a lot of tech and media companies with deep pockets in or getting into this niche, but can any of them match the $18.5 billion in streaming content obligations? 

Both stocks have defensible empires, and both investments should continue to beat the market in the years ahead. As a Netflix shareholder, I would love to give my own investment the nod here, but Facebook is the clear winner right now. It has momentum and valuation advantages, and right now that should be enough to have the upper hand for the next year or so.