What is everyone using for screen protection on their series 3?
I don't have a S3, but a S2, but, if you have the aluminum watch, the display will scratch. I use a Skinomi screen protector. First, it not only prevents scratching, it also hides the scratches already on my display, it keeps the display cleaner (no more finger grease to clean), and it does not peel. The package comes with 6 protectors in case it does peel, and you only need one package for the two watches. It uses the method of wetting screen protector with an included solution to temporarily disable the adhesive, place the protector, squeegee out the water and wait for it to dry, but you can speed the process up considerably by using a hair dryer set to low to quicken the re-adhesion.
I had used a Zagg but it did peel, and I never replaced it until I noticed the scratches.
The Skinomi is less than $8 on Amazon, the last I checked. The Amazon listing doesn't mention that it comes with six protectors, but it does.
If you have a stainless steel watch, the display is sapphire glass and will resist scratching a lot more than the Ion-X Glass on the aluminum model.