Commodore 64
http://darth-azrael.tumblr.com/post/159819807926/commodore-64
“What nobody else can give you at twice the price.”
Advertising can often be (and usually is) misleading, but in this case it was pretty accurate. The Commodore 64 was introduced in 1982 at a price point of $595 so this ad is from very early in the life of the C64. It’s only real competitors in terms of capability were the Atari 800 which cost about 50% more and the Apple II which was double the price. While each of those had their advantages, taken as a whole the Commodore 64 had superior graphics and sound and in addition to being a decent all around computer for the time was also an outstanding games machine.
After the introduction of the Commodore 64, price wars ensued with the Commodore 64 costing half as much not much more than a year later. The Atari survived as a distant competitor for a long time and the Apple II as a stronger competitor thanks in large part to its strong educational presence but all other 8-bit players were essentially eliminated or reduced to token market share. The Commodore 64 would dominate the home computer market for a long time and survived commercially almost until the end of Commodore in 1994.