i have tried steaks at both the places you mentioned, Bull Steak House (Bahria Town) does excellent steaks. The only problem they have is their location. I mean unless someone tells you in advance that here is a restaurant you wont know even if you are standing near the restaurant. It is poorly lit on the outside. However, when you go there and eat food there, you will become it fan from that moment onwards. 
I also like steaks at Captain Cook (Jinnah Super, islamabad)