Hey Ed,
I've tried several glass sealants over the past few years and some naturally work better than others. I've tried Aquapel, Gtechniq G1 Clear Vision Smart Glass, and Pinnacle GlassCoat Window Sealant.
Aquapel
Aquapel is very easy to use and since it's applied with a 6" long applicator full and complete coverage is quick and easy. The applicator includes enough product to do the windshield, side windows, and in some cases enough to seal the rear glass.
The durability of Aquapel is 5 to 6 months through a long hard New England winter. The cost is about $6.00 so it's very economical as well.
Gtechniq
Gtechniq G1 Clear Vision Smart Glass is another glass sealant and instead of using a specially designed applicator it uses round makeup pads found at most drug or department stores.
Applying Gtechniq G1 Clear Vision Smart Glass takes longer due to the small applicator and its directions indicate it should be applied twice to ensure complete coverage.
The kit includes a residue cleaner which amount to Isopropyl Alcohol and after the product dries for about 15 minutes it must be used to clear any haze.
While Gtechniq G1 Clear Vision Smart Glass does work I was surprised there wasn't more rain or water repellency while stopped or at slow speeds. The durability has yet to be determined but it has been on my truck for about 1 month and it's still working...
Gtechniq G1 Clear Vision Smart Glass is not inexpensive by any stretch of the imagination. The smaller offering is only 15ml but there is enough to coat several windshields. Cost - $17.99
Pinnacle
Pinnacle GlassCoat Window Sealant is among the latest offerings from Pinnacle. It's easy to use and is applied using a foam or microfiber pad. Apply in a circular or straight back and forth motion.
Pinnacle GlassCoat Window Sealant takes about 15 minutes or so to dry then buff off any residue with a clean microfiber towel to a crystal clear shine.
Pinnacle GlassCoat Window Sealant comes in a 16 ounce bottle and this is enough to do quite a few cars and trucks several times and cost $19.99. While the most expensive of the three it's the most economical due to the quantity provided.
Durability is still unknown but it repels rain and water very well even standing still....