The proof is in the pictures.
We got an estimate from Summit Roofing at 3 other roofers, all for repairing the same leak in our roof. Here's why we chose Summit:
1.) They were the quickest, both to come out, and to write up the estimate.
2.) They included pictures at every step of the process, and explained everything clearly.
3.) Their estimate was less expensive than most of the others. (See next point)
4.) When I called to ask why their estimate didn't include replacing the flashing that all of the other roofers had recommended, they explained why that wasn't really the problem (our problem was deterioration of the parts around the flashing), and how their repairs would make our existing flashing work like it was supposed to.
5.) They use the industry standard 2-year warranty.
Other good things:
They got back to me very quickly, even with multiple follow up calls. The workers they sent out were very nice and professional. They took pictures before, during, and after and included those in their invoice. They left the extra tiles for us (not that I'll use them, but some people might see this as a plus). Finally, their work looks great; it's very tidy and a major improvement from the black tar-like patch jobs that previous roofers had done. That section of our roof looks like brand new!