A lot is changing for two of the biggest drugmakers on the planet. Pfizer (NYSE:PFE) is merging its Upjohn business with Mylan (NASDAQ:MYL). Bristol-Myers Squibb (NYSE:BMY) just completed its acquisition of Celgene.

Investors have rewarded Bristol-Myers Squibb's moves more so far this year than they have Pfizer's. But which of these two big pharmaceutical stocks is the better pick? Here's how BMS and Pfizer stack up against each other on several key fronts.

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Image source: Getty Images.

Current product lineups

Pfizer claims four blockbuster drugs that are generating double-digit-percentage year-over-year sales growth. Immunology drug Xeljanz is the fastest-rising star among that group. However, breast cancer drug Ibrance and anticoagulant Eliquis, which Pfizer co-markets with BMS, rake in even more money and are growing sales by 20% or more. Sales for prostate cancer drug Xtandi are also climbing by more than 20% year over year.

Sales for several other top drugs are also growing by varying degrees, with especially strong growth for rare-disease drug Vyndaquel. Pfizer also has some laggards, notably including pneumococcal vaccine Prevnar 13 and immunology drug Enbrel, which Pfizer markets outside the U.S.

All of these drugs belong to Pfizer's biopharmaceuticals group, which will remain with the company after the Upjohn spinoff and merger with Mylan. Sales for many of Upjohn's legacy drugs are declining, with loss of exclusivity for Lyrica especially weighing on overall revenue.

Bristol-Myers Squibb's current lineup includes four blockbusters with growing sales: cancer immunotherapy Opdivo, Eliquis, immunology drug Orencia, and leukemia drug Sprycel. The Celgene acquisition also gives BMS three other rising blockbusters with cancer drugs Revlimid, Pomalyst, and Abraxane plus two recently approved drugs with blockbuster potential, Inrebic and Reblozyl. 

One big downside for BMS is that sales are sinking for older drugs Baraclude, Sustiva, Reyataz, and Daklinza. In addition, the company faces limited-volume generic competition for Revlimid beginning in 2022.

Pipelines

Pfizer's pipeline includes 95 clinical programs, eight of which await regulatory approval and 24 that are in late-stage testing. Many of the company's clinical programs target additional indications for already-approved drugs. 

Among the new candidates in its late-stage pipeline, two especially stand out. Pfizer's acquisition of Array BioPharma earlier this year brought the Braftovi and Mektovi combo into its fold. This combo holds significant potential in treating colorectal cancer. The company's experimental pain drug tanezumab also appears to be promising.

Before the acquisition of Celgene, Bristol-Myers Squibb's pipeline focused primarily on studies targeting additional indications for Opdivo. Now, though, the company has over 50 compounds in development.

The most promising candidates for BMS include ozanimod, which currently awaits FDA approval for treating multiple sclerosis. BMS also has high expectations for two other pipeline drugs obtained from Celgene -- cancer cell therapies ide-cel and liso-cel.

Dividends

Investors have plenty to like with both of these drugmakers' dividends. Pfizer's dividend currently yields close to 3.8%. BMS's dividend yield stands at 2.8%, but the company also just announced a dividend increase of 9.8% effective in the first quarter of 2020.

The Upjohn-Mylan merger will cause Pfizer's dividend to fall. However, Pfizer shareholders will receive shares in the new company (Viatris), which will also pay a dividend. The net impact of the spinoff and merger should leave the overall dividend payments that Pfizer shareholders currently receive around the same as what they get now.

Valuation

While both of these pharma stocks have attractive valuations, Bristol-Myers Squibb really looks like a bargain. Its shares trade at less than 9.5 times expected earnings. The company's growth prospects, even with the potential for declining sales of Revlimid in a few years, make BMS's valuation even more appealing.

Pfizer's shares trade at 13 times expected earnings. The company's growth prospects will improve significantly after the Upjohn spinoff/merger but still aren't as impressive as those of BMS.

Better buy

I like both of these stocks and own both of them. If I had to only pick one, though, it would be Bristol-Myers Squibb. I'm optimistic about the company's pipeline thanks to the big boost from the Celgene acquisition. It's also encouraging that BMS is already increasing its dividend so soon after the deal closed.