Let's not forget history that M$ has as an original developer for Apple way back in the day. They got big, competitive, then bigger, and in some aspects are what drove Apple to innovate and resulted in the great machines and OS we have now.
They still retain more market share in some segments and are still the de facto standard for business productivity suites (Office). Yes, there are Pages/Keynote/Numbers, and OpenOffice, LibreOffice, ad nauseum, but MS is still the 800lb. gorilla in that market.
Competition, no matter how insignificant it seems lately from M$, Samesung, Google and others is still what creates growth and innovation for all of us to benefit from.