LN40D550 no question. Sinotecs have cheap panels, cheap engines, high input lag, flashlighting, low response times, few settings.
A lot of people talk about their experiences and how they put their R0.05c next to a Sony and they looked the same. Don't buy their crap, they're most likely just trying to make themselves feel better about their bad purchase. True, the panel in those cheap brands aren't as bad as they used to be and a still image may actually look almost as good as a good brand but that's where it ends.
Think about it. Sinotecs are produced in China by a huge budget manufactuer. Sinotec specifically only exists in South Africa, elsewhere these TVs are marketed as PRIMA or under some other name. So firstly do yourself a favour and read some reviews about PRIMA TVs... If you're still keen think about the following: Samsung/Sony/LG etc sell millions of each respective TV model each year. The more you produce, the lower your production costs, its called economics of scale. This allows the big brands to acquire good quality input materials at low prices. The result: a better quality TV at a price which a small manufacturer could never match.
Now how many TVs do you think Sinotec sells compared to the big brand? A tenth? A 100th, maybe less. In order to be competitive budget brands have to undercut the premium brands. How do they do it: cheap inputs and less functions. The result: much less quality for a smaller price. If you compare the value for money however, nothing will beat your premium brand TV. Even their entry level models use quality inputs. Some people realise this so brands like Sinotec need to give the consumer further incentives to buy their TVs; that's where the 5 year warrenty comes in.
Next consider the money premium brands spend on and have available for R&D. Premium brands have an experience in producing TVs that budget brands will never be able to match. All the budget brand does is copy the big names. Copying, however, will only get you so far.
