I looked at roof racks at one point, and narrowed it down to these two (I wasn't concerned about drilling into the Jeep if necessary...that's what silicone sealant is for
WILD BOAR PRODUCTS: Cargo Rack Systems for your Jeep Wrangler
Garvin Wilderness Racks
Gobi was another one that I really liked...Alec at EAD Offroad here on the forum can give you info about their setup.
Some other WF links:
Roof Rack Suggestions for 4-door Unlimited?
Some links to threads from JKF:
This one deals mainly with the Gobi racks, but there's some info on the WB, as well: Choosing a cargo rack - Gobi or Wild Boar
Best Roof Rack
If you read all this, you'll have a degree in JK Rackology. Not a master's or a PhD, but a solid foundation of roof rack knowledge.