This thread has all the info you seek and more:
Jeep Wrangler TJ Cooling System Overhaul FAQ
There is
NO BETTER COOLING SYSTEM THAN THE STOCK COOLING SYSTEM, PERIOD.
Any of the "upgrade" parts you are finding are junk, pure and simple. Want to try an "upgraded radiator"? Why? What will you gain from that?
Try a Mishimoto radiator and see how long it lasts
Seriously though... I can't stress this enough. There is no "upgrade" for the stock cooling system. The stock cooling system does it's job 100% and attempting to make your engine run cooler than it's designed to will have negative effects on your engine such as decreased fuel economy and performance. The engine and PCM were designed to run within a certain temperature range.