Good luck and best wishes on buying your home. It is a fun but sometimes confusing experience.
There are no magic formulas that guarantee the information you require. The mortgage market is very similar to every other market.....shopping around will save you money. It would seem that the larger lenders could afford to offer better rates but this is not always the case.
Our recommendation is to investigate multiple resources, being certain you understand the "terms and conditions" of each before making your decision.....but don't eliminate the little guy.....that could be the source for the best rates and service.
It depends on what you are looking for. In most cases, for the lowest rates and fees, a mortgage broker will be able to shop both for you and find the best match. As a broker, I have multiple lenders I use. Some are more flexible than others, some have programs others don't.