Berkshire Hathaway (BRK.A 0.21%) (BRK.B 0.33%) stock has proven to be one of the best-performing investments of all time. Since 1980, shares have increased more than 2,000 times in value. A $500 investment would now be worth a cool $1 million.

Want to invest in Berkshire? There are two options: A shares or B shares. The ticker symbol for the A shares is BRK.A, while the ticker symbol for the B shares is BRK.B. Which Berkshire stock should you buy?

Most people should buy this Berkshire stock

Warren Buffett decided to create a second class of Berkshire stock in 1996. At the time, the price of Berkshire's original shares had exceeded $30,000. That's a lot more than most people were prepared to spend on a single share of stock.

To make Berkshire more accessible, several independent funds were preparing vehicles that would allow investors to gain exposure to Berkshire without needing to pony up $30,000. In his 1996 shareholder letter, Buffett stressed that these funds "would have marketed themselves as Berkshire look-alikes." He worried they would use Berkshire's reputation to "entice naive small investors and would have charged these innocents high fees and commissions."

In response, Berkshire B shares were created, with a starting price of just over $1,000. A-share owners had the right to convert to B shares on a 30-for-1 basis. However, B shares carried slightly weaker voting rights, with each share having 1/200th of the voting rights of an A share. But B shares still conveyed ownership in Berkshire, and at a lower price. Now, smaller investors could buy into Berkshire without needing to invest in a separately managed fund that charged unnecessary fees.

Note that the A shares have never experienced a stock split, and now have a price above $600,000. The B shares, meanwhile, have been split to help fund acquisitions, and now have a price of around $400. Many long-term investors enjoy the novelty and commitment required to own Berkshire's A shares, but for the vast majority of investors, the B shares provide the same exposure in a more affordable, far more flexible way.