Slotted, drilled, dimpled, etc. gimmick rotors are a 100% waste of $$$ on a TJ, despite the hype in the ads for things like that. The best cost-sensitive thing you can do for your braking is to install a good quality all-cast rotor like the Centric Premium and pads like EBC's Yellow Stuff which has become known as about the only pad out there that can actually give noticeably improved braking performance.
If you can afford Vanco's Big Brake kit, that's the way to go. It replaces the OE single piston calipers with dual piston calipers and the warp-prone housing that flexes so full braking force can't be applied with a reinforced housing that won't flex. The Big Brake kit together with EBC Yellow Stuff pads will make a Jeep with 35-37" tires stop like a Jeep with the factory 30" or smaller tires. This combination will make a dramatic improvement in braking.