#2 Microsoft VS Oracle

This could be fun, and an example how low can a rivalry get to. In the late 1990s, Microsoft was mushrooming; leaving behind many of its peers At this point CEO of Oracle Ellison got all freaky and hired a private contractor to buy Microsoft’s garbage to set some sneak at company’s PR practices. Ellison magnanimously offered to send Oracle’s trash to Microsoft’s headquarters. “I’m prepared to ship our garbage to Redmond, and they can go through it,” he said. 

#1 AT&T v. Verizon

AT&T and Verizon were always at loggerheads, but things really got heated up in early 2011, when Verizon got iPhone, ending AT&T’s exclusive hold on the device. The two came out openly about their obvious stiff in ads that held special significance to users. For instance, Verizon’s Test Man pointedly said, “Yes, I can hear you now,” after picking up an iPhone, which was a reference to AT&T’s perceived proclivity to drop calls. AT&T shot back with an ad outlining the inability to talk and surf the web at the same time with a Verizon-based iPhone. Apple, for once, attempted to be a peacemaker. An ad from the company stated merely that “two is better than one.”