Bun Bo Hue and Bun Rieu are my favorites here, and might be the best in town.
Restaurant is in a sketchy neighborhood. It is dimly lit with fluorescent lighting (not cool diner vibe, just makes your eyes tired vibe), there's really no decor, and the springs in the booth chairs are pretty much gone so you sink really low when you sit. The restrooms are not in the restaurant, so you'd have to go outside of the restaurant to use the restroom.
Friendly and attentive staff.