hope i can help, to be short, as mtg broker, we shop all the lenders for the best interest rate. the banks dont have that option. on any conventional or govt loan, no fee's from us, no points/origination cost, generally the bank will charge you some form of orignation/points plus their other junk fee's. shoot me your email and I'd be happy to help you out, I'm here locally in Baton Rouge.
Shop both banks and mortgage lenders, anyone saying on every product available they have the best rate is writing a pretty big check if you get my drift.. And it varies mortgage lender to mortgage lender. I guarantee I know a bank on investment loans you can't touch.
The best thing you can do is know exactly what type of loan product you are looking for (97/3, 95/5, 80/10/10, 80/20, etc....) and shop both. You may very well get the best rate from a mortgage lender, but it is not always so.