I suppose that's a question for the marketing department. It's sort of like a restaurant claiming they have the "best" food, etc. How do you prove otherwise?
That said, I think iOS is more advanced than you give it credit for. Take multitasking for example. At the kernel level, all modern OS's have similar features, etc. However, what Apple has done to allow the illusion of multitasking without taking the battery hit is truly advanced. They have applications that save states, they allow specific services to function in the background but not third party user land applications. For the end user, it's pretty seamless, but such a feat is VERY difficult to actually pull off well. They have the best of both worlds. The easy and less sophisticated way to handle it is to just allow all third party apps to run in the background, then require devices with huge batteries, higher memory requirements, etc. just for normal operations (ala Android, Blackberry, etc.).
Again, that's just one example of iOS being more "advanced" whether you personally like that feature or not.
The problem is that Android multitasking is exactly the same as Apple. Again, that's just an example of people talking without really knowing