The one I found most suitable is SELECT_CONTENT, but as the doc says:
Select Content event. This general purpose event signifies that a user has selected
You can track click of a button like this: (In my case, I have an InHouse Ad and I want to track number of clicks.)
public void openGoz(View view){
Uri uri = Uri.parse("market://details?id=com.mountzoft.gameofzeros");
Intent intent = new Intent(Intent.ACTION_VIEW, uri);
startActivity(intent);
Bundle bundle = new Bundle();
bundle.putString("goz_ad_click","1");
mFirebaseAnalytics.logEvent("in_house_ad_click", bundle);
}