I can comment only on the LG service - again that may vary depending on the location - my feedback is based on my experience in Bangalore.
My 1st LCD TV was a Samsung one, had horrible experience with service when my panel started giving problem. So I switched to LG (42LH90). After about 4 years of use, I had an issue with the power supply, raised a onsite-service request from the LG website. A technician called & came to my place the next day, checked and found the power supply board had gone bad. He then checked and confirmed the availability & price of the PS unit, it was available for 2200/-, so with my consent he ordered for it in front of me. 2 days later, the technician called & came again, with the new PS unit, fixed it, thoroughly checked it and then asked for payment with a receipt. I was very impressed - within 3 days after making a online complain, my TV was up.
I also had a very good experience while getting this TV installed 4 years back. The service guy actually came few minutes before the TV set was delivered to my place. He came with the wall-mount, installed the TV and shown me all the menu options. Contrast this with Samsung - where I had to wait for a week to get the TV installed with wall-mount, I must say - from my experienec - LG service is way better than any other brands.