Probably Nintendo. Literally no one else has a comparable career in the industry in terms of influence or success. And for such a long period too, think about how many other developers"made it big" 3 decades ago and where they are today. I also can't imagine any other "games only" company putting out successful hardware in this day and age of giant multimedia conglomerates and all-in-one boxes/handsets. Nintendo's story really does defy all odds.