I think the gap is really small now, there are some iOS exclusive apps, but there are some Android exclusives too. Most big companies will release and update Android/iOS at the same time now, things like snapchat releasing their big new update wouldn't have happened on Android along with iOS a few years ago.
Also a lot of big companies I have spoken too don't enjoy being on the App store, they lose 30% and to a big business thats millions your giving to Apple, but iOS is lucrative. The feeling I get is as soon as iOS doesn't make enough money there looking to drop it, most are praying for more money in Android.