I won the 40 inch Sony Bravia with Telkom in 2010 and I must say that tv set is THE BEST. The quality is supurb. You can see the difference between the cheaper models. Not to say they are not good but I love the sony I got. Samsung is also very good. My friend got one and its really good.
I think the best way to get a accurate display of the diffirence between the tv's is to go to a place that have the models on display and play the same blu ray on each one. That gives you a hands on eperience of what you will get. Obviously if you compare a R10 000 model with a R5 000 model there will be a big diference so keep that in mind too.
I heard people say stay away from those brands cause they suck but when you check the price gap its like R2000. So you need to decide if the price diference is worth it or not. Just my 2c