Now lets talk about the lenders. You call everyone and you do it on the same day because rates can change from day to day and you specify the loan you want. You even give everyone the same specifications down to a gnat's whiskers and you get the rates. Let us say for example a 30 year fixed for $500,000 and they ask you what your purpose is: purchase, rate and term or cash out. You're unsure so you say rate and term, meaning no cash out. You aren't interested in interest only and make that known. You are given a rate and then you compare all the rates and you're pretty sure you have found your deal.
You just may have found the best lender for you unless of course you change your mind on the type of transaction and move to a cash out loan. Then you change the type of loan as you realize that a 20 year fixed is better for you and by paying off some debt you are able to afford the 20 year fixed. Do you now still feel you have the best possible rate for you? If you do then you shouldn't have bothered with all to the above because no one lender has the best rate for every type or loan, nor does one lender have every type of loan. Unfortunately that is a true statement and why loans take a relatively long time to fund because of the ever changing mind of the borrower and the need to get the borrower the best rate which can mean pulling the loan from one lender and sending it to another.
Let me conclude with the fact that on any given day, week, month or year a lender may come out with a special on one or two types of loans, types of transactions, types of properties or for particular characteristics of borrowers and upset all the work you have put in to attempt to get the best loan for you.
My suggestions is to find the best person for you who you feel has the knowledge, the integrity and the drive to get you about as good a loan as you can get and save all of the frustration and aggravation you would have had to go through to get to a place that may not be nearly as good as your loan officer could have done for you.
I had lunch with a long time friend of mine years ago who had gotten a loan from a known bank a year or so earlier and he was telling me how good he thought it was. I asked him how he knew and he thought for a while ...... and he couldn't answer.