I'll add... the Rubicon is the most capiable stock vehicle available. As far as the TJ Wrangler, do I wish I had one over my TJ Sport? Depends. I did upgraded it to a rear Dana 44. Sure I don't have lockers, and the TJ Rubicon came with 31" tires, but it just depends what you are going to do? How much trail time are you going to see? I have so far been very impressed with what a TJ Sport can do on just 30" tires. Long term, when I can come up with the money, I'd like to put 32" tires on it with a 2.5" lift, and a front locker (I have trac-lok in the rear). Larger tires and a little bit of lift would help out get over a few things. So far I havne't gotten in a spot where I've had to have a locker (if I had, I would also want another Jeep along to pull me out if it's that bad of a spot!).
Now, as far as the JK Wrangler, if you don't get a Rubicon, be sure to get whatever model with a rear Dana 44, and the trac-lok like you mentioned. There are plenty of guys that just lift Wranglers and don't wheel a lot. But then you may get the bug and want to wheel it a lot. If that's the case, go ahead and spend the money on a Rubicon.