Stocks in companies that are essential to people's day-to-day lives are a good place to invest your money, as they're potentially less vulnerable to the market's sometimes wild swings. I'd classify all of the companies below as essential in one way or another, making them great additions to your portfolio. Investing $5,000 across these three stocks could give your portfolio some great diversification.

1. Eli Lilly 

Eli Lilly (LLY -6.75%) is as essential as it gets for patients with various illnesses that mean they need the company's drugs. From cancer-fighting drugs to diabetes medications, Eli Lilly has a diverse portfolio of assets that contribute to its growth. Trulicity was the Indiana-based company's best-selling drug in 2019, with $3.2 billion in revenue in the U.S. market and $972.7 million coming from international markets. Combined, the diabetes drug accounted for $4.1 billion and about 18% of Eli Lilly's total product sales.

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Image source: Getty Images.

Oncology drugs, meanwhile, totaled $4.6 billion in revenue last year and represented 21% of revenue. Although Eli Lilly sells essential drugs, it's not overly dependent on one drug. 

Its operating revenue grew by 4% last year and is up 12% since 2017. In 2019, Eli Lilly also banked a pre-tax profit of $5.3 billion, 24% of its top line.

In addition, the company also pays investors a decent dividend that yields about 1.8% -- just lower than the S&P 500 average of 2%. With strong diversification, a dividend, and some good, decent growth, Eli Lilly makes for a solid long-term investment, whether you're looking to add a quality healthcare stock to your portfolio or are just seeking some recurring income.

2. PepsiCo

PepsiCo (PEP 1.38%) doesn't sell life-saving drugs, but its vast array of products often find themselves on grocery lists, making it an essential when it comes to pantry loading.

The New York-based company reported its second-quarter results on July 13, and although its North American beverage sales were down from the prior-year period, its snacks and food business helped make up for that as Quaker Foods North America sales rose by 23% year over year. On the company's earnings call, CEO Ramon Laguarta noted that people are cooking more meals at home, saying this is why its food business, including its Quaker brand of products, did so well.

Overall, net sales declined by 3.1% from a year ago to $16 billion, but came in above analyst expectations of $15.4 billion. PepsiCo's adjusted earnings per share of $1.32 was also better than Wall Street projections of $1.25.

Like Eli Lilly, PepsiCo's diverse product offerings are a strength and a key reason why the second quarter wasn't as awful for the popular food and beverage company as it could have been.

PepsiCo currently pays a quarterly dividend of $1.0225. Earlier this year, the Dividend Aristocrat raised its payouts for the 48th year in a row. Investors are currently earning a dividend yield of 3% per year.

3. Adobe

Adobe (ADBE -0.98%) may not seem like a company that provides essential products or services, but for marketing and advertising professionals, it does. Its photo editing software is second-to-none in the industry, and many professionals simply can't do their jobs well without it. And with Adobe offering its products on a subscription basis, the cost is much more manageable than if consumers needed to shell out hundreds of dollars at once for a piece of software.

Perhaps it's no surprise then that when the California-based company released its second-quarter results on June 11, its numbers still looked great. Adobe's sales of $3.13 billion in Q2 were a new quarterly record, up 14% from the prior-year period.

In particular, the company's digital media segment, which includes its desktop tools and most of its subscription-based offerings, showed the strongest growth -- rising 18% year over year. The segment also accounts for more than 70% of the company's top line. The company also reported a pre-tax profit of $1 billion, up 41% from the $711 million it posted in the prior-year period.

Adobe's solid mix of products and services makes the company another well-diversified investment to hang on to for the long haul. It's the only stock on this list that doesn't pay a dividend, but Adobe makes up for that with its terrific growth numbers. 

Which is the best stock to buy today?

Here's a quick overview of how each of the three stocks are doing thus far in 2020:

LLY Chart

LLY data by YCharts.

Of the three stocks, only PepsiCo has underperformed the S&P 500, but all three stocks look to be great buys. If you're looking to add just one of them to your portfolio today, it may be worthwhile to consider their respective valuations. Here's how the stocks compare on their price-to-earnings multiples:

LLY PE Ratio Chart

LLY PE Ratio data by YCharts.

Adobe's far and away the most expensive of the three when factoring in its earnings. And that's why in terms of balancing value with growth, I would give Eli Lilly the edge today, as it's producing good results, pays a dividend, and is relatively cheap compared to the other stocks on this list.