GAF shingles do look good I will readily admit that, until the granules wear off which starts before the package is even opened.
IMO and experience GAF is one of the lowest quality shingles on the market but they have a very large marketing presence, they also have the lightest weight shingles on the market.
GAF & IKO are the only shingles I have personally seen that have blown off a roof when properly applied.
The best shingles available in my area are clearly Certainteed, Owens Corning, & Malarkey.
Compared to these 3 the others just aren't very good.
One thing I always like to remind people of is that GAF stands for General Aniline & Film, they are an old German company who made stuff for the war effort.
One of their most notorious products was a pesticide known as Zyklon-B.
Is GAF reliable, ethical, & trustworthy?