not sure in which state you are living. In California, you will go to big banks for a few reasons such as you purchase a complete new condo, banks are having seasonal promotion, sellers promise some credit if you use their affiliated bank,etc. Broker market is supposed to make mortgage market more competitive and let consumers have more alternative ways to satisfy their best interests. Either way, you will find good apples or bad apples in either industry. Company name is not as important as the reliability of the agent with which you are working.
If our broker's rate and service is same or worse than big bank, this industry should disappear based on foundational supply and demand theory of economy. If you go to big bank, sometimes you even don't have point of contact, or hold your phone for a long time before you could talk a person.