Like most other stuff. It's not the product, but the installation.

The bozo that believes product bashing is the way to go, wouldn't even be on my consideration list. ALL roofing manufacturers had lot numbers recalled or class action suits at one time or another for some product they manufactured. He no doubt needs an education in product knowledge.

The problem with most referrals is people will say the X company did a wonderful job. When in fact they really don't know what should be done, or how it should be done. There can be a leak in a roof, and not show for years because the wood has been absorbing the moisture and it hasn't gotten past the saturation point for a visible leak. Ants are a very good sign there's a moisture issue.

When you interview potential contractors. You'll want the basics from them (insurance, worker's comp, license if needed etc.). Tell them to reach back 5 years or so for past clients. They're the ones which will know if they've had problems, and how they were addressed. Don't go for the client that was just done down the road yesterday. There's no history there.

Good luck.

Also be aware there can be hidden damage that will raise the cost. A good roofer will show you and explain any problems. I'd wait for the third estimate and choose between the first and third---ignoring the second. Guy is a hack.

1) Typically, you'll want the existing shingles to be removed and carted away.

2) Typically, you'll want want new flashing everywhere. Drip edge, step flashing, etc.

3) You'll want some sort of ice/water membrane as specified by code.

4) You'll want the shingles, or "shingle system", to be installed in accordance with the manufacturers installation instructions. That results in a set of installation specifications that you don't have to put in writing. It's blanket coverage.

5) Then make sure they're bidding the same type/weight of shingle. 3-tab, architectural, 30-year, 40-year, etc.

One source I used for references was the Shingle Wholesaler. They were glad to talk to me and seemed to give me their honest opinions about quality roofers. (Yes, yes, like anything else be careful they are not being driven by profitability, or other motives.)

I ended up going with the roofer that a couple of the sales guys told me they would choose. That roofer quoted my installation using CertainTeed Landmark Dimensional.

After seven years I remain completely happy with the work. Also 3 of my neighbors have followed my suggestion and used that roofer without regret.