I spent 18 years with a window-cleaning husband who would only use Joy soap in his bucket. I know other window cleaners with even more years under their belt who swear by Dawn Dish Soap. And, of course, Detroit Sponge sells a great variety of hard-working products here. You can argue your favorite, but they all work well.
What I found interesting is this random comment I saw last week on a blog about household cleaning detergents.
I actually had a long conversation with a Dawn dish soap representative one day while trying to hunt down a certain smell of Dawn, but she told me that Joy dish soap is the same as Dawn. Said its made in the same factory. Same product. Sold by the same company under another name.
Wow. Just wow. Did you know that??