I recently had the same question. I went with the 52" Sony Bravia 120hz LCD. Coupld with Direct TV HD, the TV is awesome. With such a large TV, I'd say HD is a must.

I bought the LCD because I seriously could not tell the difference between this LCD and Plasma TVs. Typically, from what I read, plasmas have a better viewing angle, display black colors better and are better for motion (sports) because LCDs are supposedly more jaggedly. Well, I could not tell the difference in side to side comparision at all, both in movies and live sports.

I think LCD technology has come a long way. Other pluses, LCD use less engery, is better in brighter room (no glare), reliable technology and the monitors itself are a lot lighter in weight.

Not sure if its all true, but that I was thinking anyway. The clear choice in my mind was LCD.
Good luck!