The problem with Quicken Loans (and most other internet-based lenders) is that you're speaking to a telemarketer, not a licensed mortgage broker or a supervised mortgage banker. So right off the bat you're dealing with someone with limited experience and probably bare-bones training.
Another fault are the way rates are advertised and offered to borrowers. Fees can be very high... initially you'll receive a Good Faith Estimate that is light on details but sounds great on rate. Items like escrow impoundment, title work, and transactional taxes are often omitted until your application is in.
A third fault is you will work with a daisy chain of low level staffers. One will take your application and quote the lender's lowest rate. A second will "process" your loan and request documents from you. A third may call to "counsel" you about a change in rate/fees from the initial offer once the lender has your documents.
None have the authority, knowledge, or responsibility that comes with being a mortgage banker or licensed mortgage broker.
Lastly, no reputable lender or bank charges up front fees just to obtain a credit determination. An up front application fee is the surest sign of one thing: The lender turns down so many applications that they must collect a fee to cover the costs of operating the call center.
Try your bank first. Also ask your Realtor for a recommendation. Realtors have just as much interest in working with a reliable low cost lender as you since the Realtor earns nothing until the purchase closes. Good Realtors secure their incomes by working with proven professionals for the ancilliary services (like a lender) needed to close. Trust your bank and your Realtor. Ignore desparate lenders offering the moon via radio, TV, and internet.