The developers logged 3,997 distinct devices, the most popular of which was the Samsung Galaxy S II. This figure was inflated quite a bit by custom ROMs, which overwrite the android.build.MODEL variable and cause those phones to be logged as separate devices. 1,363 types were logged only once, and while some were custom ROMs bucking the numbers, a good few were just massively unpopular devices—for example, the Hungarian 10.1-inch Concorde Tab.

via Android fragmentation: one developer encounters 3,997 devices | Ars Technica.