Hi
Today's TVs don't really last long like the old CRT TVs....typical lifespan is 3-8 years....so you need to ensure that you go for a brand or model which offers you true value....
First here are some links for you to understand the difference in TVs..
LCD vs LED vs Plasma
LED vs LCD vs plasma TV - Which? Technology
Can LED LCD look as good as plasma? - CNET
CNET's guide to 3D TV: What you (still) need to know - CNET
Whats the Difference Between Active 3D and Passive 3D TVs? | eBay
Second thing for you to do is go and audition all possible brands and models....visit Vijay Sales / Croma / E Zone / Reliance Digital where you can see TVs running the same channel side by side...and see the screen from all angels....see the PQ and sound effects...most important if for you to see the connectivity options...
Only 2 brands offer 3 years warranty.....Toshiba and Sharp.....see which model appeals to you in terms of features, looks, performance etc.....and go for it....
As for me, the Toshiba PU 200 series works well, got 3 years warranty, USB slot to play almost all movie formats, multiple connectivity options...32 inch LED , front sound bar with clear sound...works well for me....got it for 25% less than mrp....from my local TV dealer and not Vijay Sales....
Some members purchased online and faced some bad experience in delivery....you can read various posts.....
Depending on where you are going to place the TV in your house and the viewing area, you should choose the size appropriately....don't get a very large one ...get something that will suit your needs and use....you may want to look at the Cricket series of Toshiba p2305