Vinegar works the best for me, I mix it strong, kind of prewash it over the water spots let it sit a little (5 minutes maybe) and run over it again with the same mix, spray with clean water wipe dry.
FWIW I have some Bass boat saver, and it works great for cleaning and waxing the boat, but it’s not so good at taking off water spots, It appears to prevent any new water spots after I applied it, but hasn’t quite taken off all the old water spots yet. I’d have to say though Bass boat saver on my glass boat is hands down the best and easiest cleaner I’ve ever used. Too bad it’s such a PITA to get (gotta order it online which isn’t hard just kind of a PITA, I’d just rather buy it locally)