It's not too hard to find biotech stocks that are bargains right now. Two of the most attractively priced biotech stocks on the market are Amgen (NASDAQ:AMGN) and Gilead Sciences (NASDAQ:GILD). Both stocks also provide nice dividend yields for income-seeking investors.

But which of these two biotechs is the better value stock? I think Gilead Sciences is the hands-down winner. Here are three key reasons why.

Four quadrants on a price/value chart with a hand drawing an arrow hitting a bulls-eye in the low price/high value quadrant

Image source: Getty Images.

1. The numbers speak for themselves

Probably the best case for why Gilead is a better value than Amgen can be found in commonly used valuation metrics. Amgen stock currently trades at 12.6 times expected earnings, while Gilead's forward earnings multiple is only 10.4. Gilead's trailing-12-month price-to-earnings (P/E) ratio of 25.6 is also much lower than Amgen's 66.5 multiple. However, the Amgen figure was artificially high due to a big tax hit incurred in 2017.

One of my favorite valuation metrics to use is the enterprise value-to-EBITDA multiple (EV/EBITDA). Enterprise value is the theoretical cost of buying a business. It's calculated by summing a company's market cap, long-term debt, minority interest, and preferred shares, then subtracting cash and short-term investments. EBITDA is simply earnings before deducting interest, taxes, depreciation, and amortization. I like EV/EBITDA because it gives a more comprehensive view of a company's financial shape than earnings-based valuation metrics do.

So how do Amgen and Gilead stack up on this metric? Gilead wins again, with a really low EV/EBITDA of 6.4 compared to Amgen's multiple of 9.6. 

2. At different stages in the game

Another reason why I think Gilead's valuation is more appealing than Amgen's is that the two companies are at different stages in the life cycles of their key products. Amgen's toughest challenges lie in the future, while Gilead's worst days could soon be behind it.

Amgen's best-selling product, Neulasta, appears likely to see biosimilar competition later this year. A key patent for Sensipar, which currently ranks as Amgen's No. 3 top-selling drug, expired in March. Aranesp and Epogen, the biotech's No. 5 and No. 6 best sellers, respectively, could both be impacted by biosimilar versions of Epogen that could win Food and Drug Administration approval in 2018. 

Gilead, meanwhile, is already several years into a major plunge in sales for its hepatitis C virus (HCV) franchise. Robin Washington, Gilead's CFO, stated during the company's Q1 earnings conference call in early May that "2018 is a trough year for us on which we can grow." 

HCV will continue to be an important part of Gilead's business, but it will be a smaller one. The company's executives think that HCV sales will stabilize later this year. Assuming that happens, the story for Gilead will focus on its other products and its pipeline. 

3. Better long-term growth prospects

Potential growth prospects are key to stock valuations. For biotechs, promising new products and pipeline candidates are paramount. In my view, Gilead has an edge over Amgen on this front.

It's not that Amgen doesn't have some potential winners. I especially like the prospects for recently approved migraine drug Aimozig. However, Amgen's partner, Novartis, will co-market the drug in the U.S. and has exclusive commercialization rights in Europe, which will reduce Amgen's slice of the pie. 

Amgen should also see sales growth in the future for its biosimilars. I think the jury is still out, though, on whether cholesterol drug Repatha and multiple myeloma drug Kyprolis will achieve expectations.

On the other hand, Gilead claims a sure-thing megablockbuster with its new HIV drug, Biktarvy. I expect Biktarvy will become the most successful HIV treatment ever, which is saying a lot considering Gilead's tremendous success over the years in treating the indication.

It's also still really early for Yescarta, the CAR-T therapy that Gilead picked up with its 2017 acquisition of Kite Pharma. The launch of Yescarta was expected to be slow due to the complexities involved with current CAR-T therapies -- and it has been. However, the drug should become a blockbuster for Gilead as a third-line treatment of large B-cell lymphoma and could see even greater success if it's successful in treating other types of cancer. 

Gilead's pipeline includes a couple of very promising late-stage candidates. The biotech could file for FDA approval of filgotinib in treating rheumatoid arthritis next year if all goes well in clinical testing. I also like the chances for selonsertib in treating non-alcoholic steatohepatitis (NASH), which could be submitted for FDA approval next year as well.  

What could change the dynamics?

There are three possible developments that I think could change the dynamics and make Amgen the better value stock. One is if Gilead's HCV sales don't stabilize. Another is if Gilead experiences major clinical setbacks. There's also the possibility that Amgen could make a game-changing acquisition that dramatically improves its growth prospects.

For now, however, my view is that Gilead Sciences is clearly a better bargain than Amgen. I think buying Gilead now could pay off in a big way for investors with a long-term perspective.

Keith Speights owns shares of Gilead Sciences. The Motley Fool owns shares of and recommends Gilead Sciences. The Motley Fool has a disclosure policy.