Mom and pop restaurants serving authentic Cantonese food is fast facing extinction in the Valley.
After Lucky's on the West side sold to a new owner who decided to Americanize the menu, HK Asian Diner's chef probably cooks the best Cantonese food in the Valley IMHO.
Hurry in before this family decides to sell or retire like New Hong Kong on Indian School in Phoenix is imminently doing. Ask for the authentic menu - don't worry it's in English.
If you prefer Northern Chinese food, then you can rejoice in the proliferation of restaurants that have opened recently, like Dinghao, Nanzhou and BJ's in Chandler and Mesa.
I expect this trend to continue where Northern Chinese restaurants continue to proliferate while Cantonese restaurants disappear, as a result of the changing Chinese population, especially students that are coming to Arizona.