Unless you need analogue, there's no difference between the BD60 & BD80. So you can save money by going for the BD60. Sony S760 has the advantage of built-in wi-fi & has a faster loading time.
There won't be any difference in the picture quality of blu-ray discs. Theoretically, S760 should offer better audio performance (although I couldn't notice any difference). But if you're bitstreaming audio to a good amp, it doesn't matter.
Personally, I would go for a Sony S760 as it looks better built & has wi-fi. Although I must say that I'm very happy with my Panasonic BD60. It's a brilliant player.