Been going to Number One Pho for years. A number of my friends told me Superior Pho is superior (pun intended) to Number One Pho. I just don't see it. The Goi Cuon (my favorite)
shrimp, pork, rice vermicelli, fresh lettuce, and bean sprouts rolled in rice paper served with dipping sauce is far better at Number One Pho not to mention cheaper. The peanut sauce at Superior Pho had a watery consistency with next to no peanuts. The one at Number One Pho was thick, rich, and loaded with crushed peanuts and the rolls were bigger.
I wouldn't say Number One Pho has a lot of ambiance but it is certainly better than Superior Pho. If I was from out of town I would have second thoughts about even walking in Superior Pho. As far as service is concerned I would say both are the same. Fast and efficient.