Some lift kits are not really good suspension systems. They just lift the vehicle up and don't afford any better articulation. A good suspension will allow the tires to flow over the terrain with lots of flexibility. Downward wheel travel is the key to articulation. It is great that the tires come up into the fenderwells and the axle bump stops work, but the real key to suspension travel is how far down it goes.
Flexibility is another important aspect of the suspension.
The steering is affected by all this movement and must be strengthened also with a stabilizer, support brackets as needed, and possibly a steering gear box support. The shock absorbers or suspension dampers, must be changed as well. A reputable company will have a matched kit for your specific vehicle and the type lift you are looking for. Don't cut yourself short by just trying to get by with one item of the kit. Save those pennies and get the kit all at once.