This week could make or break the rally.

Investors are gearing up for the busiest week of earnings with more than 140 S&P companies and 12 Dow components set to post results.

Last quarter, a number of companies warned that slowing global growth as well as international trade tensions could weigh on their bottom lines, so investors are eagerly awaiting first-quarter results to get a sense of the overall health of U.S. companies.

Among the companies set to report are industrial heavyweights Boeing, Caterpillar and Lockheed Martin, tech giants Amazon, Facebook and Twitter, and key energy players like Exxon and Chevron.

There may be many names to choose from, but Piper Jaffray's Craig Johnson and Strategic Wealth Partners' Mark Tepper agree that Amazon is the name to watch ahead of earnings.

From a fundamental perspective, Tepper believes the market is undervaluing Amazon given the growth potential outside of the company's traditional e-commerce business.

"We own Amazon [stock], and in my opinion they are unbelievably undervalued. And I know you're not going to hear that from everyone, but when you consider Amazon's growth, it's trading at a substantial discount to the S&P," he said Thursday on CNBC's "Trading Nation."

"Now of course they have their e-commerce business, and that industry in particular is growing in the low double digits, but their cloud business is where it's at. That's high margin, it's growing at over 40% per year, and it's all recurring revenue. ... Their ad business is ramping up, which is also high margin. They're actually stealing ad dollars from Facebook and Google. And no one is even talking about them in the streaming wars," he said.

Essentially, he argues that Amazon is a compelling buy here since it offers multichannel revenue streams and provides an entire "ecosystem" for its subscribers.

Piper Jaffray's Craig Johnson is also bullish on Amazon ahead of earnings, noting that the stock chart indicates a bullish uptrend.

"If you take a look at that chart you're making a pretty good-looking base, you're making a nice series of higher highs and higher lows, so I think at this point in time this is a stock that I would trade to the long side heading into earnings season. … [It's] a stock that should hold up well despite whatever the earnings release is," he said.

Amazon is set to report earnings on Thursday after the market closes. According to estimates from FactSet, analysts are expecting the Seattle-based company to earn $4.71 per share on $59.70 billion in revenue.

Staying in the tech sector, Johnson is also watching Facebook into its earnings on Wednesday. He noted that there's "certainly a lot of controversy on the fundamental side," but the stock's technicals are strong.

The stock has "reversed the longer term downtrend," according to Johnson, and it's now trading back above its 50 and 200-day moving averages, which are key technical indicators. Facebook has bounced roughly 45% since sliding to a 52-week low back in December, although the stock is still trading in correction territory — down about 19% from its July high.

Analysts are expecting Facebook to post earnings of $1.61 and revenue of $14.97 billion.

Tepper also has an under-the-radar pick ahead of earnings — GrubHub. The food delivery company reports on Thursday after the market closes, and Tepper is looking for an entry point.

"It's been absolutely pummeled this year, … so a good quarter could cause the stock to pop. The consumer is strong. The consumer wants efficiency. They all want to sit on the couch and have food delivered, and GrubHub is the U.S. leader in online takeout. They've been investing very heavily over the last few years. We would expect that to begin to slow, so margins are going to stabilize while growth continues, so there's plenty of upside here."

Shares of the food delivery company have shed about 17% this year, and the stock is currently more than 50% from its recent high. It's valued at $5.8 billion and trades at about 38 times forward earnings.

Disclosure: Strategic Wealth Partners owns shares of Amazon.