Having owned both the X and a cherokee I can tell you that they are similar in many respects, but bone stock the cherokee will outwheel the X. As far as the liberty, it is no better and in many areas worse than the X. As far as off road prowess/durability I rate them Cherokee, Xterra, Liberty in that order. If you have the money, go with a 4-runner. For the rest of us who don't have a trust fund, the X is the best thing going.

Cherokee Advantages:
Solid Front Axle
Horsepower and low end torque
aftermarket parts support in all aspects
2.72 low range tc
lightweight

Cherokee disadvantages:
Need a 3" lift and trimming for 31" tires
weak front and rear axles
unibody design (that's how it is so light)
weak rear springs
need slip yoke eliminator with any kind of lift

Xterra advantages:
body on frame = durable and easier to modify
bulletproof rear axle
32" tires stock, no lift
better (reasonable) rear springs
more interior room
integrated roof rack= one less thing to buy
headlights, I can actually see more with the low beams than I could with the high beams on the Cherokee!
reliability

Xterra disadvantages:
IFS
CV joints
autolocking hubs...either selectable or always-on are my preferences
relatively low horsepower, reasonably low torque
2.00 low range TC...least reduction in the industry
lack of aftermarket support (relative to jeep)

Now, take the Liberty with all of the same disadvantages of the cherokee. Then also take away the IFS, low end torque (not max torque, but where the torque is at), and cargo room.

As far as reliability with Jeep products, they are at both ends of the spectrum. The jeep 4.0 litre is considered a solid workhorse, the 4 speed transmission in the cherokee and NP231 transfer case are all considered very reliable in the industry. Everything around them is hit or miss. I have heard of vehicles with very few problems at up to 400k, and others that should be turned in under the lemon law. In fact, it is for this very reason that I leased the cherokee that I had. I knew if it was a good one during the lease that it would be a keeper. If it turned out to be crap, it would go back. Turns out it was a keeper, until the 14k lease buyout was 3k above what it would sell for on the lot. Since I wheeled with a few X's, new their capability and value, and didn't have a trust fund to get the 4-runner here I am with an X.

Bottom line, every vehicle has its quirks, advantages, and liabilities. With the X I have found a solid performer that will be in the stable for some time.