Microsoft and Apple- both these tech giants brought computers to the fingertips of people all around the world. Both got their start around the same time and both became iconic worldwide brands in a short period of time. Both diversified in different directions yet still competed fiercely for market share.
Disclaimer: I work for Microsoft. So, while I do have a personal opinion, I thought this was an interesting fresh look at the age old question: Mac or PC. 🙂