Two big pharma stocks have turned in solid performances so far in 2018. Shares of Eli Lilly and Company (NYSE:LLY) have jumped 24%, while GlaxoSmithKline (NYSE:GSK) stock is up 16% year to date. Both drugmakers have trounced the S&P 500 index thus far.

But which of these two stocks is the better choice for investors going forward? Here's how Eli Lilly and GlaxoSmithKline compare on three key criteria.

Three scientists in a lab

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Current product strength

Eli Lilly claims a broad product lineup across five major therapeutic categories plus its animal health business. The company is especially strong in endocrinology, with blockbuster diabetes drugs that boast fast-growing sales including Trulicity and Humalog. Lilly has also become a key player in the immunology market with a likely soon-to-be blockbuster drug, Taltz. 

The company is losing steam in two areas, however. Sales are dropping for Lilly's Cialis, which treats erectile dysfunction and enlarged prostate, due to the loss of patent exclusivity in Europe. The drug loses its U.S. patent exclusivity next month. Lilly's neuroscience drugs Cymbalta, Strattera, and Zyprexa are also seeing significant revenue deterioration.

On balance, Lilly's current product lineup has more positives than negatives. The drugmaker's Q2 revenue increased by 9% over the prior-year period. 

One of GlaxoSmithKline's biggest strengths is in its respiratory drugs, especially its Ellipta products and asthma drug Nucala. The company's HIV drugs, Tivicay and Triumeq, also continue to enjoy strong sales momentum. GSK remains a leader in vaccines as well, with shingles vaccine Shingrix off to a great start. 

On the other hand, one of the company's greatest weaknesses is also in the respiratory area. Sales are sinking for Seretide/Advair and will drop even more when a generic version hits the U.S. market. GlaxoSmithKline's basket of older drugs, including Augmentin and Avodart, are also holding back the company's revenue growth.

Does the good news from Ellipta, Nucala, and other winners outweigh the bad news from Seretide/Advair and GSK's older drugs? It's pretty much a wash. GlaxoSmithKline's total revenue in the second quarter was flat year over year.  

Pipeline prospects

Lilly's pipeline includes 21 late-stage programs. That figure doesn't include two drugs for which the company awaits regulatory approval -- migraine drug galcanezumab and its nasal glucagon product for treating hypoglycemia.

Dave Ricks, Lilly's CEO, said earlier this year that treating pain will be the "next chapter of growth" for the company. I suspect he's right. In addition to galcanezumab, Lilly and Pfizer are partnering on developing tanezumab for treating cancer pain, chronic lower back pain, and osteoarthritic pain. Lilly is also evaluating lasmiditan in a phase 3 study for treating migraine.

GlaxoSmithKline claims nine late-stage programs in its pipeline. The drugmaker has several late-stage HIV candidates and is looking to gain additional indications for Nucala. GSK also has a couple of promising vaccines in phase 3 testing.

However, the company reported some bad news last month. A U.S. Food and Drug Administration (FDA) advisory committee voted against recommending approval for Nucala in treating COPD. The FDA doesn't have to go along with this recommendation, but the chances don't look great that GSK will get a quick win.

Dividends

Eli Lilly's dividend yield currently stands at 2.13%. The company has steadily increased its dividend payout over the last five years and appears to be in relatively good shape to keep the dividend hikes coming.

GlaxoSmithKline's dividend yields 4.86%, significantly higher than Lilly's yield. However, the future for GSK's dividend could be somewhat up in the air. The company plans to tie its dividend payouts to cash flow generation starting next year. That means higher levels of uncertainty. 

Better buy

There are a couple of wildcards that we haven't mentioned. Lilly is spinning off its animal health business, which could be a positive for investors. GlaxoSmithKline is also reportedly considering separating into two businesses, consumer healthcare and pharma/vaccines. However, I don't think either of these transactions changes which of these stocks is the better buy.

In my view, Lilly is the clear winner. It has a stronger product lineup and a larger and arguably better pipeline overall. The one area where Lilly doesn't come out on top is dividend yield, but there's a chance that GSK could reduce its dividend in the future.

But while I think Eli Lilly is the better pick over GlaxoSmithKline, I'm really not a big fan of either stock. They have both generated solid returns for investors so far this year. However, my opinion is that there are simply too many better stocks to buy with stronger growth prospects over the long run.

Keith Speights owns shares of Pfizer. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.