Haven't used window cleaner in 25+ years of cleaning cars-including a job detailing them for two years at a dealer.
One damp towel, one dry towel, lots of rubbing. Make sure the towels are both very clean, washed without fabric softener, and rinsed well. If the dry towels get too wet, get a dry one. If the wet towel gets dirty, get a clean one.
I think glass cleaner is a waste of money. People are always amazed how clean my glass is.
Hope this helps.