I've had good experiences with the Centramatics. They seem to keep everything balanced especially at freeway speeds, and appear to be promoting even tire wear. They do make a small amount of noise at low speeds, but it's only really noticeable with the doors off.
Balance Masters makes a competing product using liquid mercury instead of BBs and oil. I have two of their driveshaft balancers, but have not tried their wheel balancers. I would imagine they're just as effective (maybe slightly more) as the Centramatics.