I use a Tronsmart Quickcharge 2.0 charger in my car every day. It works great.. Also, my wife's LG G4 Qualcomm 2.0 charger fast charges my ZF2 as well. I also have various other Tronsmart and Aukey quick charge 2.0 chargers around the house and they all quick charge the ZF2 just fine.
I'm sure technically there's a difference, but in my experience these all work without any noticeable difference from the ASUS quick charger in the box.