We've tried all sorts of window cleaning detergents, but have always gravitated back towards good old Fairy; the green one.
It's basic I know (but for anyone new to window cleaning), add the Fairy AFTER you fill your bucket with water and don't use too much; just enough for some suds on the glass and some slip.
Leave the bottle of Fairy in the bucket and add a bit more later, if you think you've not put enough in.
It's your t-bar, squeegy, and scrim skills that'll save you time and make life easier; not the detergent (in my humble opinion).