Most machines that are any good will weigh quite a bit by the nature of having heavy duty vac' motors, bigger water pumps etc,
Personally i use a Ninja, a very good machine, perhaps superceeded as the best around by the Eclipse, but this appears to be quite expensive at this time, and due to it's rarity at the moment will not appear on the secondhand market for several months yet.
There are plenty of good machines about, and everyone will have their own opinion, as i say mine's the ninja,