Lowe's offers affordable roof panels, tile underlayments, shingles, gutters, pipes and all kinds of roofing accessories. They are known for their cooperation with Owens Corning and there is a strong possibility that prices for their shingles will be lower at Lowe's. They have a good reputation, their prices are competitive, and they are willing to work with you. There may be some minor negative aspects, such as the possibility of bad weather delaying work, but these are relatively minor problems.
Overall, I think using Lowe's is a good option. We hired Lowe's to replace our roof mainly because the seller told us that you know Lowe's will be here and we're going to get it right. We've had several leaks and they didn't help us repair them at all. Their warranty only lasts for one year and they obviously don't support their work.
I will never use them again for any roofing work. We have been perfecting art for years and, in fact, roofing is an art, allowing us to install or repair your roof affordably, quickly and with a quality and durability that you can count on for a long time. Like you said, Lowe's outsources their roofing jobs and you're basically buying Lowe's material and they found the installer for you. In Home Depot roofing prices, you should be able to decide which company can complete your project in the shortest possible time and at the lowest roofing cost.
Lowe's would supply one of its third-party roofing contractors to install a new GAF roof system. Mom just called about her roof that she's had multiple problems with since Lowe's was hired to replace and said she has snow and ice in the attic along with mold in the bedroom. When your roof experiences problems, your first instinct might be to take things into your own hands and consult the staff of a chain like Lowes. I don't see how it is possible that Lowe's is the cheapest when it is replaced by a roofing contractor.
Lowe's offers a variety of roof repair materials, from asphalt underlayment products to high-quality shingles.