I am not getting the unreliable sentiment from people that do not own a JK or have first hand experience with a JK to make that broad of an assesment.
Latency in the throttle by wire is the perceived weakness of the engine.
Poor factory gearing choices exacerbate the automatic transmission's annoyances. Regear the differentials and the problem is solved. Again not a problem with engine.
A small number of engines were assembled in Mexico in late 2007 into early 2008. Of this small number, a small percentage of them had their rings installed with the end gaps all aligned resulting in higher oil consumption, which incidentally is covered by warranty which begs the question, what's the problem?
The only area of real I reliability is the use of both metric and standard fasteners which lead to some standard bolts being in metric holes and vice versa. Again, not an engine problem but instead a chassis problem easily fixed.
My previous Jeep was a 95 YJ with 4.0L automatic. It was much simpler and easier to work on with an abundance of space under the hood. I miss those characteristics. On the other hand I have taken my JK across the country which I never could in my YJ due to harsh bucking horse ride, deafening in cab noise, and leaking top.
The 4.0L was a good engine, but was far from perfect despite what many people claim.
I can't get past the ugly interior, especially the box gauge cluster of a TJ to own one. It is butt ugly and not well laid out. I like the interior of a CJ, when it is not covered in rust. My JK interior is nice, almost too nice. I have been taken small steps to bring back some of the utilitarian feel to it.
I had horrible death wobble for a long time in my JK which made me hate it. I finally fixed it and did some things and recently fell in love with it.
I can do more with my JK because it is more versatile. My YJ was horrible with towing but my JK is decent.
JK- easy to live with on a daily basis, go anywhere do anything
YJ- weekend toy, possible secondary vehicle
TJ- somewhere in the middle, often owned by people with JK envy who start countless threads about JK owners being snooty and not waving
None of these Jeeps are flawless. None of these Jeeps are POS. You can't go wrong with any of them as long as stay away from 4 cylinder models. Sorry 4 banger guys, but the 4 cylinder engines limit so much what you can realistically do.
I once knew a guy with 4 cylinder YJ with a top speed of 40 mph. His tires were only around 31" plus or minus an inch or two.
2014 JKU Copperhead Pearl
Too many mods to list. Too awesome to sell.