iOS Question Package names for Android vs IOS

If you publish the same app for both Android and IOS, what package names do you use?

com.mycomp.myapp for both?

or

com.mycomp.myapp.android
com.mycomp.myapp.ios

or

com.mycomp.anroid.myapp
com.mycomp.ios.myapp

or something else?

What is considered best practise?