Blue Boy has been a favorite for years- I remember my grandfather going up there and us splitting a sandwich many times.
It's sad that it didn't work out downtown- I think there was some issue with the actual location, they weren't allowed to have a fryer or open-top griddle there so the hot sandwiches weren't available. I did have breakfast and lunch there many times when I worked at FBC and one other thing that kinda hurt them was that they kinda let this mentally unstable guy just hang around in there and in the span of half an hour, he'd go from quietly talking to himself to screaming about hitler. It got to the point that if we walked by and saw him sitting in there, we'd go elsewhere and I know we weren't the only ones doing that.
As for the fox? Been there once, the greatest praise I can give it is "it was breakfast".
I think as more pho places open, people will typically just stand behind their favorites. I know saigon time has been there forever but I'm not in love with it. One time we went, the broth was really good, the other- I wouldn't have been shocked if you had told me it came from a packet. Service was okay, we were the only folks in there on both visits. But that's okay. Everyone has their favorites, ST just isn't one of mine.