LCD. Most human eyes cannot tell the diff between led lcd and plasma so go for the economics.LED is a newer technology there fore more expensive.The image creating surface of LCD consumes less power than plasma,LCD displays last up to 60,000 hrs while most plasmas last up to ,20,000 hours.
1080i or p. All HD TV programs are broadcast in 1080i. The only true source of 1080p are some video games and Blu-Ray dvd's. LCD's are cheaper than Plasma for similar size TV's.
I have a 47in LCD in my living room, and a 56in rear screen LCD projection in my Theater room, and they both give excellent crisp high resolution images.
But the best way to choose is go to a showroom and look at them side x side. Make your own choice and don't listen too much to the salesman.Best Buy is a good place to get info. The salesmen aren't on commission and are usually willing to take time to show you around.