well android and iphone are taking the market and from what i have seen blackberry is really struggling but their coming out with a new os that will allow for a lot of apps and since theirs not that many now for blackberry if you get on it early enough you can really take the market, but thats under the assumption that blackberry will actually take off again
You forgot to mention Windows 7.5 and 8 - it is possible that smartphones based on these OS's could pickup during next year.
I think when it comes to the iPhone you have to be looking at what the iphone 5 is capable of doing, check stuff like siri and see if that can be integrated within apps, to control them easier, I am an iPhone user so I can only really speak about the iPhone, I think Blackberry has some catching up to do, I dont think the Blackberry has the choice of apps that android and the iPhone has. I think in the gaming world iPhone and Android are doing well, this is where Blackberry falls behind but then again it isnt marketed as a gaming phone it is more about business and it is strong with blackberry BB, I think if apple made there own official facetime/ app IM (like blackberry bb) app, then it would do very well, maybe it would be called iM or iIm or something Who knows, we will have to wait and see I guess
hmm, I think it's according to the customer needs. But in my opinion, Android are good one, because they have google behind him.