Tackle Tour reviewed the Wave Away screen cleaner and seemed to like it.
Eye cleaner works great too as Lake said. Costco has their Kirkland brand that comes with two spray bottles and a couple microfiber towels. When you run out of eye cleaner, there's a dispenser of eye cleaner that they have there. As long as you have the spray bottle you purchased originally, you can go there and get refills free of charge.
#3804, "RE: Best product for water spots on fish finder screen?" In response to Reply # 0
Bought the $5 eye glass cleaner at Costco. Wow, awesome. My screens are clean in seconds. Cleaned my laptop screen and my monitor while I was at it. That's a great tip, thank you guys. Free refills are you kidding me? LOL.