I have to say, finding the best mortgage lender was the EASIEST part of buying/owning a home. Seriously. I think we got quotes from five companies, and yes, we took a momentary, small hit to our credit scores, but it was all a wash by the time we signed the mortgage papers. We looked at a few large national banks, but we actually got the best rate and no additional points with a local lender (who eventually sold our mortgage to a national bank, but that's what they do).
I highly encourage you to get pre-qualified and have your lender decision narrowed down before you start shopping. When you do fall in love with a house, you will be in the best possible financial position to make an offer if you're pre-qualified and have it all figured out already.
And if you're struggling with all the options at this stage, maybe re-think how much you want to buy a house right now. 'Cause it only gets worse! :-P