In the middle of refinancing now, 3.5% for a 30 year with closing costs paid (around a 2-2.5k credit) seemed to be the best offer I could get. I went with GoodMortgage but was also looking at Better Mortgage (haha, looking at this now the names sound ridiculous). I always just pick the top 3 companies on bankrate.com with good reviews and then see which one can give me the best offer.
Oh, and one pro tip: make a folder NOW, both digitally and irl, to keep all of the mortgage stuff in for easy reference. Scan everything you can. You'll be sending things off left and right and it's easier if you're organized from the outset.