In Manhattan, there's the Gem Spa on 2nd Avenue and 8th street that still makes egg creams. Haven't been there in about five years, but last time I was there, they made a "perfect" egg cream, even though the store clerks were of Indian ethnicity. I advised the clerk that his egg cream was "perfect" and he returned a very proud smile.
In Queens, Eddie's Sweet Shoppe on Metropolitan Avenue in Forest Hills still makes great egg creams. I've never been to Hirsch's in Brooklyn, but they also have a reputation for still making these drinks like they were made 50 years ago.
Junior's makes egg creams, but I haven't tried them. Their glasses have etchings to mark the proper amount of syrup and milk.
I happen to like my egg-creams sweet.
For those who make your own, while it's known that you must use Fox's U-Bet Syrup, Fox's U-Bet, like most other syrup and soda manufacturers, generally uses corn syrup (boo!) or a combination of corn syrup and sugar. But corn syrup is not kosher for passover, so around passover (in April), most manufacturers put out Kosher for Passover versions of their products and those only contain cane sugar and are far better.