If you're looking to invest your hard-earned money in a large technology company, then the odds are that Apple (NASDAQ:AAPL), as well as Google's parent company, Alphabet (NASDAQ:GOOG) (NASDAQ:GOOGL), have popped up on your radar. 

Apple dominates the premium smartphone, tablet, and smartwatch markets and is making strides to shift more of its business toward recurring services revenue. Alphabet rules search, offers a diverse array of popular services, and is expanding its consumer hardware business in a significant way.

Two girls using iPhone XR devices in an Apple store.

Image source: Apple.

If I had to pick only one of these two stocks to add to my portfolio, though, it would be an easy decision for me: Alphabet. Here are two reasons why.

Stronger core

Apple's core business is the iPhone, which made up nearly 63% of its sales in fiscal 2018. Alphabet's core business, on the other hand, is advertising, which it reports in two distinct categories: Google properties and Google Network Members' properties. These two categories made up roughly 83% and 17% of the company's total advertising revenue last quarter. Advertising revenue, in aggregate, accounted for roughly 86.2% of Alphabet's overall sales.

Apple's iPhone business isn't in great shape right now. Indeed, the company announced on Jan. 2 that its sales for the first quarter of its fiscal 2019 -- the peak quarter for the company's all-important iPhone product line -- would dramatically miss the company's guidance due to poor iPhone sales "primarily in Greater China."

It looks like, at a minimum, that this iPhone cycle is totally shot.

Alphabet's advertising business, on the other hand, is alive and kicking. Last quarter, Alphabet reported that its advertising revenue grew by a solid 20.3%. While Alphabet hasn't reported its fourth-quarter results, the company announced on Jan. 4 that it'd next release its quarterly earnings on Feb. 4. When a company sets an earnings date without providing updated guidance, it's generally a sign that the quarter didn't wildly miss the company's previous guidance. (Although there's risk that when it issues new guidance, it'll be lower than what Wall Street expects.)

Nevertheless, analysts currently expect that Google will post 20.4% revenue growth when it reports and that it'll guide to revenue growth of 19% for the following quarter. If they're right, it'll be crystal clear that Alphabet's core business is solidly intact while Apple's is showing cracks.

Better growth prospects

In the coming years, analysts are predicting significantly faster growth for Alphabet than they are for Apple -- and I don't blame them, given the preceding discussion. Analysts now appear to expect the Mac maker to see sales decline by a little less than 1% in fiscal 2019 from 2018 levels before growing by 4.3% in fiscal 2020 and then 1.5% in fiscal 2021. 

That's just not exciting. 

Alphabet, on the other hand, is expected to deliver robust growth over the next few years. For its fiscal 2018, analysts expect it to turn in 23.1% growth followed by 19.2% growth in fiscal 2019 and then 17.5% growth in fiscal 2020. 

That's much better. 

Not only does Alphabet's advertising look set to continue to thrive, but the company's opportunities elsewhere look promising. For example, Alphabet's Google has been in the consumer hardware business for a while, selling devices like smartphones, tablets, and smart speakers. One analyst even thinks that hardware could generate nearly $20 billion in sales and $6.1 billion in profit for the search giant by 2021.

To be fair to Apple, the company is successfully diversifying beyond smartphones, but that could be offset by weakness in the core business. For Alphabet, those adjacent opportunities should serve to augment a core business that's already thriving.

Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Alphabet (A shares), Alphabet (C shares), and Apple. The Motley Fool has the following options: long January 2020 $150 calls on Apple and short January 2020 $155 calls on Apple. The Motley Fool has a disclosure policy.