This question gets asked a lot, so I decided to make a FAQ out of it.
While everyone has their own opinions, my opinion (from trying out multiple seat covers for my TJ) is that the IGGEE seat covers are second to none. They seriously fit so well that everyone who gets in my TJ always asks if it came factory with leather seats. The first is just so, so good! You really don't even know they're seat covers.
Here they are (yes, they are cheapest to get on eBay oddly enough):
1997-2002 Models
http://rover.ebay.com/rover/1/711-5...0001&campid=5337789113&icep_item=142093052380
2003-2006 Models
http://rover.ebay.com/rover/1/711-5...0001&campid=5337789113&icep_item=141980088740
I'd love to hear everyone else's thoughts on what seat covers they have, how they fit, how you like them, and a link to where to get them.