97-99 tj is the best platform to start building from. There are more after market options, the aftermarket is more affordable, they have the better motor of pretty much all 4 litres, and certainly better then the 3.8
From mild to wild the TJ is still the most supported platform with the most options available.
Considering most well kept 97-99 tjs are going for 3-6k, when it comes to modifying and creating a part time driver, part time toy, its a bit of a no brainer.
Spending 15k on something that is eventually planned for considerable modification is not really the better of the option.
Dont forget if you go new, and then modify, you're pretty much garrunteed to have warrenty woes. Everyone here has been through that before. You spend 30-40k on a new rig, part of which goes towards warrenty, and when the time comes to use the warrenty you risk not being covered because of the mods you did.
That is never fun.
If you get in with a 4k$ jeep, and dont have a 700$/month payment, and mandetory full coverage insurance, you can afford to pay for those major failures yourself and not worry about being covered or not on a warrenty.
For under 10k you can run beadlocked 32's on a 97-99 tj with a small body lift, small tummy tuck. You will do every trail this club does and out perform stock jk's and rubicons for less then half the money.
I have run and built everything from bone stock tj's, xj's, and zj's to every level of mild to wild that someone can imagine.
for starting from scratch, the 97-99tj wins every time.