Even before my Jeep came in, first mods I bought were Genright front bumper (already had a winch sitting in my garage from a prior vehicle,) lockers, gears, front and rear Antirock sways, ARB compressor, Genesis dual battery.
I haven't installed any of them yet because I love this thing so much as it is! I'll get to them one of these days.
Arb dual compressor. Why? Because traction and comfort are nice on the trails, and driving at 15 psi on roads is sketchy as hell. Not cheap but it works great and should last quite a while with the occasional usage it will see
OMG, first I started with replacing the cloth interior with leather, and well, $20,000 of mods later I'm still having fun looking for things to add and do!