Biogen (NASDAQ:BIIB) is a great company, even though it's hit hard times lately since the revelations that the company's biggest blockbuster, Tecifdera, might cause progressive multifocal  leukoencephalopathy (PML) -- a potentially deadly brain infection. The multiple sclerosis (MS) drug's growth has slowed considerably. I'm bullish on the stock's potential with incoming data readouts from its exciting next wave of potential mega-hit drugs -- nusinersen, anti-LINGO, and aducanumab (for spinal muscular atrophy, multiple sclerosis, and Alzheimer's, respectively). That's why I'm a proud shareholder. But for investors looking to increase their healthcare exposure, there are three stocks I think are better buys today: Gilead Sciences (NASDAQ:GILD), Celgene Corporation (NASDAQ:CELG), and Johnson & Johnson (NYSE:JNJ).

Gilead's stock is stupid cheap

According to analysts polled by S&P Global Market Intelligence, Biogen is supposed to achieve $17.67 in GAAP earnings per share in 2016, which means it's trading for a P/E of roughly 16 times 2016 earnings. Gilead, by contrast, is trading at 7.9 times 2016 earnings. And while Gilead's largest product, Harvoni, has seen its growth sputter like Tecfidera, that's because of discounts to maintain an eye-popping 90% market share in U.S. hepatitis C sales. Gilead also dominates HIV treatment in a way Biogen has never managed in multiple sclerosis, with 74% market share among treatment-naive patients. And Gilead is investing in a robust and expanding pipeline -- with simtuzumab, which has blockbuster potential in nonalcoholic steatohepatitis, and filgotinib, an intriguing inflammatory disease drug, both top of mind for investors. When you add in the 2%-plus dividend yield and substantial share buybacks, it's hard not to see Gilead as a slam-dunk opportunity.

Celgene has fewer question marks

Celgene Corporation is heavily levered to its multiple myeloma drug Revlimid (which represented 63% of company revenue in Q1 2016), but management is projecting strong growth for the company's other major drugs over the next few years. The cancer drug Abraxane is expected to bring in about $1 billion in 2016 (around 9% of total anticipated revenue), and the autoimmune treatment Otezla is on a fast ramp, with over $1 billion in sales expected in 2016. Unlike Biogen, Celgene doesn't have a couple of tent-pole drugs in its pipeline that centralize its risk; management has done a great job of diversifying the pipeline through a number of licensing agreements. With big opportunities in immuno-oncology and a host of other diseases -- and with management projecting that revenue and adjusted EPS will more than double to $21 billion and $13 per share, respectively, by 2020 -- Celgene has clear, stable growth ahead.

Johnson & Johnson is more diversified (and stable)

With its recently announced spinoff of its hemophilia business, Biogen's management is slimming the company down to focus more on multiple sclerosis and developing its diverse pipeline (particularly nusinersen and aducanumab). People usually like management focusing where they're experts...but Johnson & Johnson is a huge exception to that rule. The conglomerate is diversified across medical devices, pharma, and consumer products (like Band-Aids and Tylenol), and it continually chugs out slow, steady, reliable growth. With anticoagulant Xarelto posting 29% year-over-year sales growth last quarter, and Invokana/Invokamet up 18%, pharma continues to drive the company's overall growth. Johnson & Johnson is a Dividend Aristocrat (meaning a stock that has grown its dividend for at least 25 consecutive years), and its dividend yields 2.8%. For the income-focused investor, it's hard to argue that Biogen would be a better pick.

If you only had to buy one...

My money's on Gilead. Truth be told, I own every stock I'm talking about in this article. I think all four of them are great businesses with lots of interesting opportunities ahead of them. But Gilead's valuation has gotten so out of whack with the stock's substantial business prospects -- and management's superb history of capital allocation -- that I believe it's easily the best buy in large-cap healthcare today.

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.