Crutchfield has a nice article on their web site, as well as lots of other resources, to help you decide - it's not a simple one is always better than the other.
Here's the URL for the article:
http://www.crutchfield.com/Learn/lea...flatpanel.html
My Mom just got a Sony KDL32L4000 - I was pleased with how smoothly it deals with fast-moving images, and how true the colors seem next to other flat screens in the same size class at the store. Granted, I haven't seen the XBRs, but they are quite a bit more expensive, and my Mom didn't want to spend a fortune on a TV.