Android: Developers can code in basically any C variant, and java and mono will work with private frameworks. In android, the fragmentation means your app is never guaranteed to work with any device on any SDK or any software version. In spite of this issue, the hardware is quite good, but the carriers put in the software significantly slow things down sometimes or prevent certain features from working.
IOS: Objective-C is an easy language to learn. IOS hardware is also very easy to work with a significant advantage over android. But, IOS hardware is slightly slower than android in terms of overall speed, but the apple UI elements mean that your users will have a better experience with anything you code. You also have access to apple support documents.