Apple iPhone, it has many more apps available, and Apple controls the update process so that all phones can update whenever they like. Android phone updates are controlled by the service providers such as Verizon and Sprint, and they would rather have you buy a new phone instead of giving away operating system updates. So most Android phones are running old versions of Android.
I would say iPhone because Android is so overused in almost everything these days that you won't find a good up to date one that is cheap. iPhone's are great for about everything but come with a few bugs like freezes and app crashes but it's not the phones fault 90% of the time its the user.