I find that Certainteed easily has the best quality control.
I can honestly say that I have never had **any **issues with the Landmark line, of any kind, ever.
I recently had a batch of Landmarks where every other shingle had the laminated portion misaligned by a little less than 1/8".
The dragon teeth hung below the main body of the single, it was consistent though.
We had to snap our lines @ 11" to correct for it and the roof still came out perfectly straight.
This minor defect was rather common with Cambridges, Oakridges, and Timberlines.
Probably still is...
Packaging plays a role here, the Landmark shingles are more tightly wrapped and hold the shingles in alignment in the package much better.
The GAF shingles are not tightly wrapped, as a result the shingles move in the package and the sealing strips become misaligned with the release film.
The result of this is that sometimes the shingles will seal together in the package.
When you go to pull the shingles apart they are sealed together and they rip.
So now you have to set these damaged shingles aside and sort them so that you can use them in valleys and on rakes where you can cut off the damaged portion of the shingle.
More time wasted dealing with a defective product.
But I suspect many simply don't do this and just slap them on as is...
In the GAF packaging there is always one shingle that has the sealing strip seal to the wrapper.
This makes it more difficult to remove the packaging and the shingle that has packaging sealed to it is unusable, it has plastic covering the sealing strip, so if you install it, it won't seal, it can't...
We throw this shingle away with the packaging stuck to it.
You don't have to worry about wind blowing the wrappers around because there is a shingle stuck to it.
Kinda like if you have your teeth knocked out you don't need to go to the Dentist...
When you open a package of Timberlines there are always a lot of excess granules.
This makes the roof slippery and is a safety hazard.
I don't suppose this has anything to do with Timberlines losing most of their granules in 10-12 yrs...
Even the pallets the Certainteed shingles come on are of higher quality.
The boards on the pallet are more closely spaced so that the wavyness you get from shingles on the bottom of the pallet is less pronounced.
Compare this to a GAF pallet and you can see why there are threads on roofing.com asking "why is my roof all wavy", "how long before the roof lays down", etc.
I find it very hard to believe that an actual installer likes these shingle.
The only conclusion I can come up with is that they simply have not installed Landmarks and they just don't know any better.
This is normal for them and they are used to it.
I can see how salesmen likes these shingles, they don't have to work with them and GAF is very helpful to the salesman in pushing their products.
All that being said, the GAF shingles do look nice and once the uphill battle of correctly installing them is completed they will perform just fine.
When the granules start falling off of them, well we can just sell another roof.