I think you should take a closer look at this, it might help you make a chioce.
+ Tons of quality apps on the app store
+ Lovely build quality (iPhone 4 only)
+ User Friendly
- Not capable of very much unless jailbroken
- Closed ecosystem, no modding the phone's operating system at all
+ Amazing third party support, even better than the retailer or company
+ Superb modability
+ Capable of a ton out of the box
+ Variety of different phones to choose from
+ Everything is very open
However this will really depend on what platform you like and what appeals to you, i would go for Andriod, it is open source and lots of android application are available and its google products, Also there are many of it to choose from.