Don't be fooled by mortgage companies advertising such things as:

"WE HAVE THE LOWEST RATES IN TOWN!!"  or
"NO DOWN PAYMENT, NO CLOSING COST..." , etc. 
I know you are not going to believe this, but RATES are not the most important part of the loan.  RATES are as personal to your needs as the home you are financing.  Your particular situation may call for a little higher rate which would offer no PMI rather than the lower rate with PMI causing a much higher monthly payment.  And you might want to consider that PMI payments are not tax deductable and interest payments are.  Your higher interest rate may have a built in "tax advantaged mortgage insurance" factor. 
If lender "A" quoted you a 5.5% rate for a 30 year fixed and lender "B" quoted you 6% for a 30 year fixed which would you go with?  If you said lender "A" due strictly on the fact that his rate seemed lower, you would be doing yourself a great injustice.  You need to do your due diligence by exploring further with lender "A" to see if all of the other factors that make up a loan suit your needs and that you qualify for that particular rate.