I used seal and shine by turtle wax but after I clean glass with distilled vinegar and water , then window cleaner then applied seal and shine, always squeegee the glass, you will always get spots but it will be easier To clean next time
I used Rain-X on one pane, and Mothers CMX on the other. After a year of use, the Rain-X is garbage, and the mothers still doesn’t even of, let alone stain.