Which HDTV should I buy?

I have two tv's that I'm looking at. Both are Samsung. The first one is a 42" plasma with 720p and sells for 550 dollars. The other is a 40" LCD with 1080p and sells for 600. The plasma has 600hz, 1ms response time, and better contrast ratio than the LCD. The LCD has 60hz, 40,000:1 contrast, and a 6ms response time. Not sure what to get. Which is better and more worth it? not sur