Warren Buffett’s favourite Apple stock has delivered around 42% returns over the past year, but with John Ternus set to take over as CEO, investors are watching whether the iPhone maker can maintain its strong performance.When Tim Cook took charge as Apple CEO after Steve Jobs in August 2011, many people questioned whether he could successfully fill the shoes of the legendary founder. However, as valuation expert Aswath Damodaran puts it, Jobs provided the "foundational boost" with a 47.19% compounded annual return; Cook added an astounding $3.64 trillion in market valueAs John Ternus takes the reins, Damodaran said the new CEO must find his own path, acknowledging that Apple is now a "mature, cash-returning and more cautious company." While there may never be a Hollywood movie about Tim Cook's "operational pragmatism," his legacy of restraint is a management quality that deserves an "ode" of its own, according to the valuation expert.Also read | Is Tim Cook a better CEO than the legendary Steve Jobs? Aswath Damodaran shares his argument for Apple investorsWhat lies ahead for Apple shares under the new CEO?Apple shares soared a whopping 2,300% under Tim Cook’s legacy. Now the question remains how much returns the stock would deliver under Ternus’ tenure. “Steve Jobs left huge shoes to fill, but Cook is also leaving big shoes, albeit of a different type, given his very different approach to expanding the company’s growth engines,” Bloomberg quoted Chris Brigati, chief investment officer at SWBC, as saying.“He has certainly done amazing things as CEO, and every shareholder has benefited, probably more than was expected when he took over,” he added.The returns delivered by the iPhone-maker's stock seem even more impressive when investors consider the dividends. During Tim Cook’s tenure, Apple shares climbed a whopping 2,736% on a total-return basis, Bloomberg reported. This is impressive when compared to S&P 500’s 769% surge, including dividends, and the tech-heavy Nasdaq 100’s 1,512% surge during the same period.Warren Buffett’s top stock pickMeanwhile, Apple remains legendary market investor Warren Buffett’s top stock pick. He once joked that Apple’s outgoing CEO Tim Cook made more money for Berkshire Hathaway’s shareholders than he ever did as CEO of the iPhone-maker.Berkshire invested about $35 billion in Apple during the period between 2016 and 2018. That $35 billion investment then rapidly surged to around $185 billion before tax, including dividends and gains, Buffett was quoted by Business Insider as saying. "And I didn't have to do a damn thing," he added.Also read | Will Google be Berkshire CEO Greg Abel's best stock pick after predecessor Warren Buffett's Apple bet?(With inputs from agencies)(Disclaimer: Recommendations, suggestions, views and opinions given by the experts are their own. These do not represent the views of The Economic Times)