My favorite Chinatown dive was a place called the Silver Restaurant on Washingon Street. It was incredibly cheap, incredibly seedy -- and very good, at least for what you paid. As a college student, I could stuff myself for $8. Later it rose to like $12. It was open for years and years, and then one year I went back -- and it was gone!

SF Matt turned me on to the R&G Lounge, which has better food and the atmosphere and service are like the French Laundry compared to the Silver Restaurant. Much more $$$ though.
For big timer Chinese Restaurants, the two competitors were always the Empress of China Rooftop Garden (very expensive and very bad) and the Imperial Palace (very expensive and quite good). Tommy Toy's is the newcomer to that niche, though by now it is very old. I haven't been in eight years, I think, but I liked it when I was last there.