For me, there seems to be a direct connection between immaculate glass and the pleasure (not to mention safety, esp. at night) of driving. I've tried every glass cleaning product known to Western Civilization, including things that were not intended specifically for glass.
What seems to be optically best, in my opinion, is Stoner's Invisible Glass. It's not the easiest to use because it may require 2 or 3 applications, or until you get all the contaminents off. But the end result is superior, indeed invisible glass, which is what you want. The glass seems to stay cleaner for a longer time too.
Some of the popular class cleaners that are available virtually everywhere, notably that BLUE stuff with the name virtually synonymous with cleaning windows, contains wax. Yes, that's right, wax. My theory is that they put wax in their products so that your windows get dirtier faster than if there was no wax, hence more product is sold. Wax streaks, picks up dirt and is harder to clean off unless you use more of the stuff that put it there in the first place.
GM makes a glass cleaner that is supposed to be used to clean the "glass"(actually Lexan) roof panels on Coupes. Okay. I've found it's not quite as good as Stoners.
Until something better comes along, that's what I'll be using.