http://gizmodo.com/5407745/a-guide-t...-right-for-you
imo you can't go wrong with any of the three. i don't know why ppl are samsung whores. I know for a fact that employees and companies make more on samsungs, because their cost is unbelievable. I'm not biased to Sony, and I haven't been shopping for TVs lately, but the XBRs really look nicer than the Samsung's or Toshiba's whenever I walk browse around a store. All the ballers tend to get a pioneer plasma (if you can get your hands on one now), or a sony. Not the right place for trends or arguments lol but that might tell you something.
You're right about samsung and sony receiving the same panels though. it's a lot of speculation but I've read that from the same batch, Sony buys the higher quality ones from a batch while Samsung takes the rest, while selling the worst to brands like dynex.
update:
another link that helps you decide. these two should be stickied so we don't have to repeat and repeat
don't get hung over specification differences of 1-2ms, 'dynamic' contrast etc. they're pointless. go to the store and stare at them. google up a guide to look at tv's in stores. they like to turn up the brightness and make the ones that they make the most money off of look the best (*cough samsungs).