Something else. Apple is hugely suceessful and profitable despite the fact that the programming languages and frameworks used to code Apple apps are inferior to .NET/C#
(Well, yes and no).
But as far as multimedia and user-experience is concerned, Apple's frameworks are both olderand ahead of Microsoft's offerings. Common Controls doesn't hold a candle to Aqua. GDI doesn't compare to Quartz and Core Image. WPF is not conducive to a great user-experience because it isn't native (in both sense of the word), doesn't integrate well with the host, and has large initialization delays.
Objective-C is aiming for feature parity with C#, and you can use C# on OS X and iOS anyway.