Jack has an iPhone 5, but he's thinking of switching to an Android phone. Leo says that we've reached a point in smartphones where they're all fantastic and he can actually choose based on the phone he likes and not the carrier he's with. There's a lot of choice and it varies on what he likes.
Leo says that the HTC One is one of the top of the line phones with stereo front facing speakers. There's also the Motorola Moto-X, which has the charm and feel of an iPhone but is more advanced in many areas. Even the Nokia Lumia 1020 Windows Phone is a great option.
But don't write off the new iPhone 5S. iOS 7 has some great features including a particle engine and if he already is in the Apple ecosystem, it makes sense to stick with it.