What year is your Jeep?
First and foremost, you'll want to see if that leak at the manifold is a crack in the manifold itself, or just a old / leaking exhaust gasket.
If it is the manifold itself, don't waste your money on a new one. Simply take it to any competent welder and have them weld the crack. DO NOT under any circumstance be led to believe that 'headers' make a difference on these engines. The headers they sell for the 4.0 found in the TJ, are not even full headers, and therefore you won't gain any real power.
Next up after the exhaust manifold you'll want to replace your stock mid-pipe (the pipe that has the pre-cats in it) with a new one.
Bosal makes a good replacement mid-pipe, with both the cats already in it:
https://www.amazon.com/dp/B0049AYRFQ/?tag=wranglerorg-20
After the mid-pipe is replaced, your best bet is to go to a competent exhaust shop and have them build you a cat-back exhaust. I had this done for around $250, which included a nice Magnaflow muffler.
You'll also need a catalytic converter (
https://www.amazon.com/dp/B000C946KE/?tag=wranglerorg-20) to replace the one that is under the vehicle.
Do not be tricked or fooled into paying $500+ for one of those Borla (or similar) bolt-on catback exhausts. They're wayyyyyy overcharging you for those things, because an exhaust shop will build you one for around $250 like I said.
Unfortunately there is no all-in-one solution for the TJ (like there would be for some performance vehicles). You have to piece it all together using the pieces I mentioned above (or similar).
That isn't that big of a deal, you just have to be prepared to spend a little, because catalytic convertors are never cheap (and if you buy some cheap Chinese one, it make create running issues or check engine lights with your vehicle).