I always enjoy Lotus Blossum in Sudbury for American style Chinese Food. Everything is very tasty and they have a very nice buffet lunch. Agree with SG Framingham rec for Sichuan. Also, you're only about a half hour from Gene's Chinese Flatbread in Chelmsford. Other threads will fully describe what to get there (Hand pulled noodles, etc.), but be aware that it's more a takeout / counter service place than a restaurant.
how far are you willing to go? Because the best Chinese food is in Framingham: Sichuan Gourmet, Uncle Cheungs, and Red Pepper are all excellent. And all are on route 9 in Framingham.
I;ve had tolerable Chinese at Mandarin Westborough and Cheng Du II. Not great, but good in a pinch, if those are any closer.