So are you saying your TJ won't go places your previous vehicles would? I can't imagine sand and forest trails that your TJ can't handle.
Anyway a stock JK isn't going to go many places your TJ won't unless you are talking a Rubicon. Guess it boils down to which style you like. If you like the TJ you can certainly modify with axle upgrades, gears, lockers, tires etc... That's what I would do and would be a lot cheaper than upgrading to JK Rubicon. I wouldn't consider a non-Rubicon JK an upgrade in terms of off road capability.
Also you will get a lot more response to questions in the other sections such as TJ, JK or General. This section is mostly for introductions.