I find that lender guidelines are remarkably similar. The difference comes down to service. Who communicates with you best, is well referred in your community, and guides you through the often challenging lending process.
Ask for a personal referral from friends, family, and colleagues. You can also try Yelp and look for well rated mortgage lenders.
In addition to shopping for best rate, I encourage you to ask about lender fees - request a good faith estimate. I have found huge differences in what lenders charge in back end fees.