Sony HX920 will give you best picture quality but if you are looking for size, Sharp should be your preferred choice. You might even want to take a look at their 80-inch TVs.
What is the price difference between the two in your country?
The Sony is at 3863 euros and the Sharp at 3670 euros.
For budget reasons we are also looking a the sharp LC 6 840 E (2000 euros) and the Panasonic TX P 65 STE 50 at 2260 euros.