I ran a 3" lift for 5 years. was good all round set up but did need a bit better ramp over angle. I used king coils & lovels shocks. found these brands top notch. I then went 5" used dobbinson which sagged to about 3.5"s in the front & around 4" in the rear within the first month. I ran 30mm coil spacers in the front for a short time before tossing the lot & going 6" tough dog kit. Happy with the brand.
Mines all engineered so no probs not that the coppers really worry about lifted fourbys around here. I reckon a 4" lift would be the best all round set up. The 6" I run is great out in the bush but it dose leave the on road a little to be desired. I also find it binds the tie rod up on the drag link. I'm mucking around with a few different things to try & get it to drive better on road & sort out the binding issues. It's not bad but no where as good to drive on road when it had the 3" & sagged 5 down to about 4" kits in.
It all depends on how much you have or want to spend. I recommend to anyone asking me what height to go too, go 4" just from my experiences. I'm thinking of going back to 4 or 5" coils
Anything over 2" needs to be engineered which is no real issue cost me $900 & that included the turbo as well. Do some esquires in your state & see what you can get away with. The law is about to change I read making the laws national. This will make it better for some states & maybe not for others but at least it will all be the same for every state. As atm as soon as I drive mine out of state it can be defected.
cheers.