I'll say right up front that Ha Gow certainly doesn't serve up the most delicious dim sum I've ever had in the city, but the friendly service (family-run business yo) and a handful of their dishes that I find particularly tasty keep me coming back. Doesn't hurt that they also deliver, which is generally my preference over dining in their cheery but no-frills restaurant.
My favourites include the steamed shrimp dumplings, the spinach, garlic, shrimp dumplings, and the sticky rice. I just noticed that someone else listed those as their faves as well, so you probably can't go wrong with those selections.