I and many other more experienced Jeepers will recommend any model year Rubicon or TJ
except 2005-2006. 4.0L engines from those two model years have an oil-pump drive assembly problem that is not always easily fixed, or fixed for long. If you want an LJ Rubicon, I'd stick with a 2003 or 2004 which are far more trouble-free. My 2004 has been fine.
Also, the 6-speed is a lighter-duty transmission that gives more problems than the previous NV3500. The 6-speed was only available in the 2005-6 models so you'll either have to settle for the better/stronger 5-speed or go with the automatic which is a better transmission choice for more technically challenging course. Not because you don't have to shift, because the automatic gives an infinitely low 1st gear ratio and it multiplies torque (yes) 2-3X over that of a manual transmission (yes too) when you're accelerating up & over an obstacle or leaving from a stop.
The nice thing about going from a JK to a TJ is that TJs are a LOT easier to work on and modify. Good decision to go that way!