I'm an Android handset owner, and I'm considering expanding my skills to develop for Android.
My answer is that it depends. If Apple don't object to your app or business model, then the iPhone is probably the better bet, for now, and until and unless the number of Android handsets greatly outnumber iPhones (i.e. even with a lower customer conversion rate, the absolute numbers then tip in favour of Android).
Factors that limit the money available to Android app developers include a) lots of free apps to choose from; paid apps need to offer something special - even many trivial apps for iPhone seem to be paid b) handset manufacturers' lack of co-operation with Google in getting their firmware releases approved by Google for copy-protected Market apps makes it more likely that potential customers will just download illegal copies of your app because it's actually easier than buying it. Fail.