So I've tested Warid and Zong side by side for almost two weeks now. In my opinion Zong is offering a far better service than Warid, in Karachi.
Almost at all locations in Karachi (the places i visit anyways) Zong has had a better ping, speed and coverage. While at places Zong will loose LTE and come on 3G, for Warid it meant back to 2G.
Now I need to and get my Warid sim closed.