LED/LCD or Plasma TV buying confusion ?

Ok. I'm in the market for a new TV and I was in the mall today. There were several TVs side by side.

The one I really liked was a Sony Bravia 42 inch LED Smart TV. It cost around $1000. It had Wifi ,Lan ,webbrowser and all that stuff. I know I'm not going to browse on my TV and I can live without wifi. However I'm not sure if LAN is all that important.

Then there's a 50 inch LG Plasma screen for about 750 dollars. The screen size is quite appealing here compared to the Sony but I noticed a visible quality difference between the Sony and the Plasma Lg screen. I don't know if it was just because it was a big screen or something to do with the source. Also the LG was 1080i not 1080p ,how much of a difference does that make ? I noticed that the Sony was simply brighter and it everything on it just popped out of the screen while the LG one had softer picture and it just didn't look as good.

In theory ,does LED/LCD tech outperform plasma ? I definitely saw a noticeable difference from about 4-5 feet away. My normal viewing distance will be 11-12 feet. Please advise.