I want to buy lg smart led TV mobel no 42ln5720. Lg is good brand or not, I need idea regarding above model.

Yes its' fine.

Korea has taken over the world TV market, with Samsung and LG, two excellent companies.
And that model seems to be available for $700 from places, so that's a good price for a smart TV. I like LED over LCD partly because of much lower electric usage and heat emitted from the vents.
If that model has no black border, even better. The borderless TVs are fantastic. More TV in the amount of space.