I've only tried two, Alfredo's and Mama Melrose's, and I wouldn't exactly rush back to eat at either one. I found the service to be merely adequate at both places (with a thinly veiled contemptuous attitude, oddly enough, from both servers), and the food was mostly fair-to-middling, Olive Garden type Italian American at both locations--nothing that particularly set my tastebuds afire, but then again, nothing that made them blanche in disgust either.
Bottom line, if you find Olive Garden to be the height of Italian Cuisine (and if you do, you really should expand your culinary horizons), then you should be perfectly content with either Alfredo's or Mama Melrose's.