My personal preference is Samsung, and recently bought the basic Q series model after a bit of Internet research as it seemed to be one of the best in my price range (slightly more than the one you linked without getting into the £1000+ range of OLED etc) . However the Panasonic was the second choice on my list and in your scenario I’d be tempted to go for it as its:
– slightly cheaper
– 4 HDMI sockets compared to 3 on the Samsung
– Dolby HD support, which seems to be a common standard for 4K video services
The Hitachi looks like a branding exercise and is unlikely to match the picture quality of the “proper” TV brands. If you want to save a bit of money over the more established brands, Hisense seem to be the manufacturer who can undercut them and still produce a decent TV.
