It is often useful to use the APR for comparision since that generally includes all of the costs associated with the loan, especially with a honest lender that will include all the fees in the APR.
Edited – also make sure to compare the good faith estimate (GFE). All lenders are required to give you one that will help to estimate the costs associated with the loan. Obviously you must compare apples to apples in the sense a 30yr fixed with a 30yr fixed. Go line by line to compare the costs of various fees such as credit report fee, appraisal fees, inspection fees and any points, etc.
Edited again: I think a good starting point is bankrate.com On the front/main page there is a place to find a mortgage rate. Then the next page select state and city and it will give you the rates for 700+ FICO scores with 20% down.
