I like Golden Mushroom on 9W in Upper Nyack near the intersection with Christian Herald. Although it's one of those places that serve Chinese and Japanese, it is still good and the owners are very nice. They have great sushi too if you don't want to stick exclusively to Chinese.
EDIT: Also try Jade Village in Spring Valley.
Fortune Garden on Rt. 59 across from Red Lobster has pretty decent food for Rockland Co. Chinese. I like their sesame chicken, steamed pork dumplings, scallion pancakes, and Shanghai style noodles. I haven't found a place better then this for Chinese in Rockland, but would love to know if there were any I am missing.