Nearly everything is going right these days for Eli Lilly (LLY 0.08%). Sales and profits have been soaring. So has the share price, jumping more than 50% year to date after a 59% gain in 2023. Lilly now ranks as the biggest healthcare company in the world. The drugmaker has more room to grow, with its obesity drug Zepbound and a U.S. approval for Alzheimer's disease drug donanemab likely on the way.

But is Eli Lilly the best biopharma stock to buy right now? Nope. I think investors should buy another magnificent biotech stock instead.

Not exactly David vs. Goliath

Which stock do I have in mind? Vertex Pharmaceuticals (VRTX 0.26%). However, we're not talking about a David-versus-Goliath kind of matchup between Vertex and Lilly.

Sure, Vertex is much smaller than Lilly, with the latter's massive market cap at over $840 billion. But it's by no means small: Vertex's market cap tops $120 billion, making it one of the world's largest drugmakers.

Its stock performance hasn't been too shabby either. It's beating the S&P 500 so far in 2024, after jumping nearly 41% last year.

One nice plus for Vertex is that it enjoys a monopoly in treating the underlying cause of the rare genetic disease cystic fibrosis (CF). All four approved therapies that fit the bill are marketed by Vertex, including its super-successful Trikafta/Kaftrio.

Vertex's massive opportunities

I like Eli Lilly's growth prospects; obesity, type 2 diabetes, and Alzheimer's disease present especially lucrative opportunities for the biopharma giant. But Vertex has massive opportunities too.

The company could have its most powerful and profitable CF therapy to date on the way to market. Vertex is awaiting U.S. and European Union approvals for its vanzacaftor triple-drug combo, which targets CF.

Meanwhile, the commercial launch of Casgevy, as a one-time functional cure for sickle cell disease and transfusion-dependent beta-thalassemia, is ramping up. The gene-editing therapy seems likely to become another blockbuster drug for Vertex.

Don't think Vertex is limiting itself to rare diseases. It expects to soon complete a rolling submission to the U.S. Food and Drug Administration for suzetrigine (VX-548) in treating moderate-to-severe acute pain. Suzetrigine should have enormous potential as a non-opioid drug in the multibillion-dollar acute pain market.

The company has also advanced inaxaplin into a late-stage clinical study targeting APOL1-mediated kidney disease (AMKD). There are no approved therapies that treat the underlying cause of AMKD -- and it affects more patients worldwide than CF.

There could be another late-stage program in Vertex's pipeline soon; the company's acquisition of Alpine Immune Sciences should close any day now. This deal will add povetacicept to Vertex's portfolio. The experimental drug has shown promise in treating IgA nephropathy, a serious autoimmune disease affecting the kidney. As is the case with AMKD, there are currently no approved therapies treating the underlying cause of the disease.

Vertex has other earlier-stage pipeline programs as well. I'm especially intrigued by its type 1 diabetes program -- Vertex thinks it's on the right track to developing a cure with its islet-cell therapies.

Where Vertex clobbers Lilly

If we went line by line comparing Vertex's current products and pipeline candidates with Eli Lilly's, I suspect Lilly would come out on top. However, there's one area where Vertex absolutely clobbers Lilly.

Shares of Eli Lilly trade at more than 64 times forward earnings, and the stock's price-to-earnings-to-growth (PEG) ratio using five-year growth projections is 2.6. Vertex is dirt cheap in comparison: Its forward earnings multiple is a much lower 29.6, and its PEG ratio is only 0.64.

I think both Lilly and Vertex have impressive growth potential. However, much more of Lilly's expected growth is baked into its share price than is the case for Vertex. Eli Lilly's a good pick for biopharma investors, but Vertex Pharmaceuticals is an even better choice.