Sometimes, when a stud mount fails to hold, the problem is with the method of applying the glue rather than the glue itself.
If you are simply trying to squirt glue into the hole you will end up with a number of studs not actually bonded. What happens is the stud can simply push the wad further into the hole without actually being firmly grabbed by it. The glue needs to be applied to the stud rather than the hole.
The easiest way to do this is to insert the stud into the nozzle of the glue tube. Trigger the gun till the nozzle is almost full then push the stud in all the way. As you pull the stud out it will be evenly coated. You can vary the amount of glue left on the stud by triggering the gun as you pull the stud out. This method works even when installing to "problem" substrates, such as sheet metal facades. Also, if you want just a thin coating on the stud, such as on an inside job where you want little or no glue visible, cut the nozzle with a smaller hole.
Trying to insert glue into the hole is messier and ineffective for many of the holes, and you will go through a lot more adhesive. I watched a demonstration once that used a cutaway brick so you could see what was happening to the glue as the stud was inserted. A glue wad injected into the hole was pushed forward ahead of the stud instead of engulfing the stud. It would sometimes even fall down into the hollow of the brick, rendering that stud not bonded at all and wasting adhesive.
The particular brand of glue is not as important, in my opinion. It just needs to be an adhesive that dries soft, that allows the stud to float in the hole. A glue that dries rock hard will not allow movement and this can cause a flat plastic letter to bow due to expansion.
I have used pads very little in the past 40 years, and then only at the insistence of a client who requested no holes be drilled. I don't care for the look of pads. I have on rare occasions nutted the studs. This has been when the surface was a false facade of sheet metal, easily accessible from the back. Even then, nuts were gently finger tightened rather than tightened with a wrench. Some of the nuts backed off on their own over time, perhaps due to vibration, and in retrospect, I would have used nuts with nylon inserts, but still not snugging them tight against the back of the facade.
Brad in Kansas City