Tom's right. Referrals from others that you trust are your best source to find people you can rely on.
For loans, the answer is not always obvious. Wylie is USDA-elgibile, which means your best bet on the mortgage company would not be your typical Dallas/Plano loan officer.
For Realtors, there are several criteria that you'll need to check into, but nobody rates them. During your initial phase you have to establish a budget for your purchase (it's usually best to consult a loan officer first) to figure out how much you have to put down and how much to spend each month.
Your Realtor actually starts helping you in the next phase where you give her a set of things you want or need in the property, such as location, price, schools, features and so on. The Realtor's ability to find candidates is crucial during this stage.
The next phase is to negotiate with the seller. Often Realtors can find you something, but negotiating is not the same skill set.
Once you have a contract, your Realtor should be guiding you through the maze of inspections, loan processing, and other paperwork, plus some additional negotiating may be needed.
In the last phase you will be closing, where the mortgage company again comes into play. Today, loans are taking longer to process and close and often special obstacles arise that your Realtor and your loan officer can help you prepare for.
If someone rates loan officers on finding the right type of loan, processing your paperwork reliably and accurately and in time for closing, I don't know who that would be.
If someone rates Realtors on locating properties, negotiating, dealing with paperwork and closing, I don't know who that is either.
Again, your best bet is to consult people who had positive experiences recently and can suggest someone to interview.