It can be tough to choose between two partners. Mario or Luigi? C-3PO or R2-D2? Tom or Jerry? I wouldn't want to exclude any of them. 

With a new bull market potentially near, investors might be forced to soon make such hard decisions. Vertex Pharmaceuticals (VRTX -1.02%) and CRISPR Therapeutics (CRSP -1.35%) stand out as real-world partners in the biopharmaceutical industry. Both stocks could be attractive to growth-oriented investors. But which is the better bull market buy? 

An easy decision in a bear market

If we were talking about which of these biotech stocks is the better pick for a bear market, it would be an easy decision. All we have to do is look at how Vertex and CRISPR Therapeutics stocks performed in the bear market last year.

Vertex stood out as a huge winner in 2022. Its shares soared more than 30% while the major indexes plunged. The company's strong revenue growth and rising profits played a big part in that performance.

Investors no doubt liked that Vertex enjoys a monopoly in treating the underlying cause of cystic fibrosis (CF). While some companies worried about rising interest rates and inflation, Vertex didn't have such concerns.

CRISPR Therapeutics didn't fare so well. The stock plunged nearly 50% last year.

Take all of those positives we identified for Vertex and throw them in the trash. CRISPR Therapeutics doesn't have any approved products on the market to generate sales. It remains unprofitable. 

Unsurprisingly, Vertex is definitely the better bear market buy. However, with a new bull market possibly right around the corner, CRISPR Therapeutics stock is surging a lot more than Vertex is. 

Common denominators and differentiators

Vertex and CRISPR Therapeutics share several common denominators. Most importantly, they're partners in developing exa-cel. Both companies stand to profit significantly if the gene-editing therapy wins regulatory approvals in treating sickle cell disease and transfusion-dependent beta-thalassemia.

But it's fair to say that CRISPR Therapeutics would receive a bigger boost from those approvals than Vertex would. The smaller company will receive 40% of all profits from sales of exa-cel. Those profits will make a much bigger impact on CRISPR Therapeutics' fortunes, though, than they will for Vertex.

The two partners are also working together on developing VCTX-211, a potential cure for type 1 diabetes. CRISPR Therapeutics initially teamed up with Viacyte on the program. Vertex, however, acquired Viacyte last year. In addition, Vertex has its own internally developed type 1 diabetes program.

Each company also has other pipeline programs to watch. Vertex is gearing up for potential near-term commercial launches of non-opioid pain drug VX-548 and the vanzacaftor/tezacaftor/deutivacaftor triple-combo for CF. The big biotech is also evaluating inaxaplin in a pivotal clinical study targeting APOL1-mediated kidney disease, an indication with a bigger patient population than CF.

CRISPR Therapeutics has a potentially registrational study underway of CTX110 targeting CD19+ B-cell malignancies. It's testing CTX130 in an early-stage clinical study for treating solid tumors and some blood cancers. The company also plans to advance cancer cell therapy CTX112 into clinical testing this year.

Vertex can also bank on more growth from its CF franchise. The company recently provided full-year 2023 revenue guidance of between $9.55 billion and $9.7 billion. The midpoint of this range reflects a year-over-year increase of 7.8%.

Better bull market buy?

I think that CRISPR Therapeutics is likely to deliver a stronger return than Vertex in a new bull market. Investors could once again turn to higher-risk stocks.

CRISPR Therapeutics stands out, in my view, as one of the more attractive members of this group. It could truly be an explosive stock this year.

However, Vertex is much less risky than CRISPR Therapeutics. Regulatory wins for exa-cell should provide a nice catalyst (albeit a lesser one than the company's smaller partner would receive.) Most importantly, it's still not a sure thing that a new bull market will materialize. If not, Vertex would almost certainly outperform CRISPR Therapeutics. 

My personal pick between these two partners is Vertex. I think it's a winner, regardless of what the market does. And if I absolutely had to choose, I'd go with Mario, C-3PO, and Jerry, too.