Blackberry in mobile OS share had it for a while, though I'm sure you'd argue that it doesn't exist anymore, but you had asked about ever, not just right now. Video game consoles are another example, with the Nintendo, Xbox, Playstation.
In just about every market there exists two natural economic leaders - the quantity (a.k.a. cost) and the quality leaders. There are market leaders other than the natural two who can arise through other means, such as ecosystem lock-in, tech patents, brand exclusivity, or some other method.
Blackberry in mobile OS share had it for a while, though I'm sure you'd argue that it doesn't exist anymore, but you had asked about ever, not just right now. Video game consoles are another example, with the Nintendo, Xbox, Playstation.
In just about every market there exists two natural economic leaders - the quantity (a.k.a. cost) and the quality leaders. There are market leaders other than the natural two who can arise through other means, such as ecosystem lock-in, tech patents, brand exclusivity, or some other method.