The main difference between the two is the LJ is longer. Other than that, there isn't much difference.
Superior offroad? It depends. In most cases LJs will do better with climbs like waterfalls and such due to the wheelbase. In tight twisty obstacles/canyons the TJ may be able to maneuver a little better since it is shorter...not necessarily a deal breaker though. An LJ may just have to take a different line.
Ive never actually driven an LJ, but I would guess the wheelbase makes them a little smoother on the road as well as handle better...all things being equal.
That being said, I have a TJ and would trade it for an LJ in a heartbeat.
__________________ Poor Boy Racing The definition of the EVERYMAN Challenge!
The LJ has a 10" longer wheel base, an extra 2" of foot room for the rear passengers, an extra 13" of rear cargo space and all LJs came with a Dana 44 rear axle. Offroad, it all just depends on the kind of wheeling you do. If you want to climb sandstone in Moab, the LJ is going to be superior. If you want to maneuver through a heavily wooded forest, I could see the turning radius of the TJ being better. I could go farther but, as you can see, they both have their advantages and disadvantages. With that said I wouldn't trade my LJ for anything.
I've always liked the TJ better. More sporty look. If I want to haul more, I use my F-250 PSD. If I want to just cruise the roads in the summer or hit the trails, I take the TJ. Just a matter of personal opinion. If it's your only ride, then you might need the more room vehicle.
I have an LJ Rubicon and the extra space is great if your doing long runs where you want to carry gear. Someone mention the D44 in the rear and that's true. The ride on road is way better than a TJ, especially at freeway speeds. I wheel with my nephew who has a TJ Rubicon and there is nowhere his TJ will go that the LJ will not. With respect to parts, there is plenty of after market for LJ specific parts but many are interchangeable with the TJ. I bought mine and had no difficulty finding a lift kit and rock rails (the LJ specific parts, I think the spring rates on LJ is different than the TJ). Bumpers, roll cage, skid plate, wheels and tires all are interchangeable with TJ's. Bone stock the TJ looks better, but fixed up they're about the same.
I have a TJ, but I have the jeep and a 2nd vehicle. If I only had one vehicle, I'd go with the LJ. You'll have useable trunk space. With respect to the ride, longer wheelbase is generally better for the same spring rate, but not by much IMO. I don't think my TJ Rubicon's ride is noticeably any better/worse on the freeway than my M3, unless you're talking handling of course, so it can't be that bad. Both will shatter your kidneys, but that's how I like it. FWIW, my dad's F-350 super duty is a worse freeway driver than either, and that has a wheelbase longer than the Mississippi.
Storage space is the big thing. I like the look of a TJ better than an LJ, but sometimes I wish I had more space to store stuff. They both will climb about the same. I have seen obstacles that a LJ struggles on when a TJ has no problem and vise versa. You cannot go wrong with either one.
2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 33" or 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up
I just picked up a low mileage LJ after originally looking for tj at everyones advice. I can say...for my purpose the extra space is very handy because i have the bestop instatrunk in the back I lock my laptop in and can store my softtop windows between the gap of it and back seat. Plus i will be towing some so the added wheelbase and towing capacaity will come in handy too.
The storage is awesome! you can actually fit 4 dudes and a cooler of beer in the trunk! Now that i have 2 kids, the extra rear seat room and trunk mean that it's still usable where my last tj would not work. when you take the back seat out its almost as much room as a small truck. I didn't notice any difference in ride quality.
__________________ my 06 LJ rubicon
2.5" SL, 1" BL, DIY highline, 35s with double beadlocks.