If you take a look and analyze featured items, you would see criteria of selection.
First, the mood and genre/category of track. It is mostly happy/inspiring, corporate (not a genre, but whatever), and indie rock. So we can say that Envato represent mostly such a way of music standarts on its market. So if you write electronics, cinematic music, downtempo, ambient and other stuff I am not sure there are big chances to be featured.
I dont know is it bad thing or not, but sometimes I do not understand such a logic to put in one line almost similar tracks,moreover, some of them not selling at all. Why such tracks being featured? I do not know.
The one thing I could say for sure, this is not the thing you should bother about, because you can not affect it somehow. 
Cheers