I have always thought of East Side Imperial Garden as the best in town (altho we really liked the old Red Pepper).
At work we order deliver mostly from Jade Garden and Hong Kong Cafe (House of Lu!!), altho there are plenty of things from each place I'm not all that fond of.
We have hosted Chinese interns at work over the last few years, from Shanghai, and our friends a couple years ago said Yen Ching on Midvale was "the most authentic" in town and they enjoyed it. We went there and they "negotiated" with the house to get us some special stuff served family style and it was great. I've been there other times and it was also very good.
Our current interns took us to Fugu this past week, said it was their favorite restaurant in town. I thought it was very good. We Americans ordered the lunch "combo" and there was plenty of food - egg roll, lettuce salad with a ginger salad, grapes and fresh pineapple chunks, and the "main dish" (I had sichuan beef, very tasty, tender, lots of good veggies too). The interns ordered hot and sour seafood soup for all of us - basically your garden variety hot and sour soup, but with scallops, shrimp, and fish in it. Wonderful. Then they ordered three dishes for us to pass family style - a sweet and sour fried fish (really nice), a beef dish that I didn't get the name of, served room temperature (I assume that was on purpose) and very good. And Pork Intestines - yes, listed like that on the menu. An acquired taste, we all thought. The texture was, ummm, kind of intestine-like, you know?
So, I really recommend Fugu and Imperial Garden and Yen Chiang.