I used Hi-Tech PMR for several years when I lived in the Dallas area. They were great to work with and I trusted them. The main advantage I found was that I could drop off my scrap, go across the street to Roseco and pick up whatever findngs and tools I needed, run down the street to a couple of gemstone dealers and pick up whatever stones I needed and then return to PMR and pick up my settlement.
Now I live in Durham, NC and have no such local vendor support. I use Elemetal (which used to be NTR) now, The main reason is that with a twenty minute drive, I can take my scrap to the Raleigh location and be headed back to the shop with my settlement in about twenty minutes. Gone for an hour, no shipping charges or delays.
I usually get my settlement back as pure gold grain and the Raleigh location of Elemetal sometimes only has an ounce or two in stock, so I'll have to wait for the rest to be shipped from their Dallas office. No big deal, an ounce or two is usually all I need to get through the three or four days it takes to ship from Dallas anyway.
Elemetal has a whole bunch of offices and they can all do the same thing that the Raleigh office does for me. You might check the website to see if there's one near you. https://elemetal.com/locations
If you're not in a hurry and don't mind paying the shipping charges, I could definitely recommend Hi-Tech PMR.
I've also heard great things about David H. Fell, although I've never used them for refining. H&S is OK, but they can sometimes take forever. Stuller also provides refining (or should we properly term it as 'buys scrap'), and like H&S, you can use it to pay a balance.
I don't think you can go wrong with any of the real refining companies. It's the guy that shows up every year with a bunch of cash and Suisse Credits that I would worry about getting a fair shake from..