Karthik bro, my 5 cents:
1) Please check & focus on the model also and not only the brand. For example, many Samsung models may have better AV quality than models of Sony or vice versa.
2) Please consider Refresh Rate & Screen Resolution as the two most important technical parameters of picture. However, please see/ hear the actual AV quality for the specific model (with DTH input and not some fancy HD Video) in a showroom even if you are buying online.