A lot of businesses that were left for dead during the COVID-19 pandemic are finding new life again. This is especially the case for companies in the travel sector.

Take Carnival Corp. (CCL -0.66%). The cruise operator's stock is up an impressive 135% in 2023 (as of Dec. 22). Credit goes to strong consumer demand and revenue, an entirely different situation from three years ago.

However, I think investors can find a better stock to buy in order to gain exposure to travel and leisure. Keep reading to learn why you should forget about Carnival and add Airbnb (ABNB 0.75%) to your portfolio instead.

It's easy to find faults with Carnival's business

To give the business the credit it deserves, Carnival has been enjoying outstanding momentum in recent quarters. In the latest fiscal year (ended Nov. 30), the company generated $21.6 billion of revenue, a record. Management also said bookings and pricing trends were very strong.

But if we zoom out and focus on more important factors, it's easy to find faults in the business. For starters, Carnival will likely struggle tremendously in a recessionary scenario. Given that the Treasury yield curve has been inverted since the summer of 2022, a clear sign of an impending economic downturn, Carnival might experience a huge slowdown in the not-too-distant future. And this is worrying.

I'm also not a fan of the balance sheet. The business currently carries more than $30 billion of debt. That's a large sum, especially when you realize Carnival's market cap is $23.7 billion. This adds a lot of financial risk to the equation that is best avoided.

Airbnb has numerous attractive qualities

Like the situation with Carnival, investors could also say that Airbnb would be adversely impacted in a recession, as consumers spend less money on travel to focus on tightening their budgets and conserving cash. But Airbnb is staring down such a huge growth opportunity that an economic downturn might have muted impacts.

Management estimates the company's total addressable market in the trillions of dollars, which includes new experiences for travelers to choose from and new tech features to increase engagement, price transparency, and safety for all users. There's a lot of optionality to continue growing revenue.

It's incredibly obvious that Airbnb has far more growth potential than Carnival. And for long-term investors, this creates a key tailwind to produce strong returns.

Plus, Airbnb possesses powerful network effects thanks to its two-sided ecosystem of guests and hosts. There are currently more than 7 million listings on the site, with 113 million nights and experiences booked in just the last quarter. As this platform gets larger, it becomes exponentially more valuable to all stakeholders.

Airbnb shares have risen 65% this year, which is a remarkable gain. However, that's less than half the return that Carnival put up. As of this writing, the travel platform's stock is still 35% below its peak price.

I can see why some investors would assume that Airbnb is trading at an expensive valuation right now. After all, this is the case with a lot of growth-tech stocks. But shares go for a forward price-to-earnings (P/E) ratio of 16.8. That's not expensive at all, and given the attractive characteristics I just described, might even mean the stock is undervalued.

And when compared to Carnival's current forward P/E multiple of 20.3, Airbnb looks like an absolute bargain on a relative basis. If we look out over the next five or 10 years, I don't believe anyone can come up with a valid argument for why Carnival's stock will generate better returns than Airbnb.

This makes the latter business the much better one to own in your portfolio.