The best over the counter kit is probably Rubicon Express Extreme Duty 4.5" kit, hands down.
Most everyone else's kits are all very old and don't take into account that people want a soft ride. Or if they do they tend to wear out quickly.
What you'll also find out is that many leafs aren't even make by the company selling them. Most are from a company called McCoy Brothers in Canada. Funny thing is McCoy Brothers will sell kits directly now.
http://www.mccoybrosusa.com/. Still there are some leafs they make but do not sell. Lift lits like the Pro Comp 4" is the exact same leaf as the Rubicon Express 4" but a bit cheaper. Rubicon Express's 4.5" used to be made by National Springs which is well known for their nice leafs, but they changed that a few years after the leafs came out. I'm not sure who makes them anymore.
Leafs like Superlift and Skyjacker tend to be on the soft side and they usually end up sagging prematurely or bending under use. They have a good warranty but a 4" lift should not turn into 2.5" with sporadic use offroad. Stiff leafs can be made to ride softer. Many settle to where they put the shackle at the wrong angle and cause unnecessary stiffness. The other problem is that the factory and leaf mfg. have you overtighten the leaf spring bolts. If you use nylock nuts you can run them looser without having to worry about the bolts falling off. IIRC, stock is around 75-90lbs-ft which is very tight. Also, when installing a lift you need to make sure not to tighten the bolts all the way until it's on the ground and you've cycled the suspension a little. You don't want to preload the leafs.
The other thing to keep in mind that YJ's has 3 different sets of leafs stock. 2.5L with soft tops used the lightest while the 4.0L's with the Hardtops uses the heaviest. Most suspension mfg.'s are building their springs with the 4.0L in mind so if you have a stock 2.5L with no bumpers or winches, it will probably ride stiff. The best way to get around this is to do your own home work and buy custom leafs. Typically custom leafs are sold at a set price so you will pay the same for 1" as you would for 6". You will usually tell the builder what you do with your Jeep and about how much gear you bring. This is so they can get an idea of how much weight you normally have in addition to the Jeep's weight. You will have to source your own shocks, U-bolts, U-bolt plates, bump stop extensions and anything else necessary for the lift. If you're running stock shackles, you might want to consider upgrading as the stock shackles aren't that strong and usually have wallowed out holes. They also cup around the rubber bushings creating extra friction. If you're cheap you can get some 3/8" or 1/2" plate and make your own shackles.
Personally, I wouldn't bother with any off the shelf kit and go straight to some custom leafs. It's more work but has greater rewards.
