I bought a 6 ton bottle jack from Home Depot after my factory scissor jack broke. The bottle jack is MUCH easier to use than the scissor jack, but it is not perfect. In particular, the model I have doesn't go high enough to lift the LR3 from the jacking points. I end up having to put blocks of wood underneath the bottle jack to give it extra height. I can get around this by jacking up the car from the control arm, but a different problem occurs when you later lower the jack. The vehicle ends up "grounding" it self on the jack, and you have to raise the air suspension to get the jack out.
Overall, I think the bottle jack is better than factory scissor jack, even with the above mentioned problems. The factory jack is way too fragile and slow.