Samsung will give you better value due to its price and overall design/features. Its new D series models are sleek, with thin bezels and have very good internet (Smart hub) functionalities. Prices are good too as compared to Sony models.
However, if you want best picture quality especially for movies and sports, you should opt for Sony models. Due to better picture processing and panel technology, Sony always produces deeper blacks (for movies) and better processing of fast moving pictures (for sports). They are expected to launch their 2011 models by next week, so you may want to have a look at them as well. The only negative side could be prices, which would be higher than Samsung.