You might enjoy a visit to Addiction Aquatic Development. It's a group of shops/vendors and open plan restaurants, ranging from fresh seafood to various styles of cuisine. Pretty vibrant, interesting, busy place.

For classic beef noodles, you could try Yongkang Beef Noodles. Gets very busy so I suggest going outside of peak lunch/dinner times if you can.

Really, I would just try to eat as much XLB and beef noodles as you can manage, at any place that looks busy with locals. No need to target the famous places.