CBQ with no doubt. Their range of services and their network are really convenient for customers add to this their accurate customer service.
CBQ is the best bank in Qatar when it comes to a number of services like Online, call center. (I also have account in QNB and I know quite well about Doha Bank) IBQ doesn't have online service at all.
Network, CBQ is the bank that has the widest presence in malls (Hyatt, Villagio, city center, lulu HM, Landmark) with all convenience this brings to customers in terms of proximity and working hours.
Customer service in CBQ is better than that of QNB and Doha bank. I'm not talking about people who smile only but about their accuracy and professionalism as well.
They may be less flexible than other banks but for me personally I preferred their services over all other banks (and I have dealt with many of them)