I looked into big screen TVs for a while before I picked mine up. I think part of it is personal preference, but I would recommend going to a best buy or a circuit city where they have a large selection of big screen TVs (tweeter doesn't have as large a selection). Take a look around and see which style of picture you like best.
My personal preference was the DLP because they're a nice compromise between a plasma and a traditional big screen. The DLPs have higher resolution than most rear/front projection TVs, and I liked the quality of the picture better when compared to projection OR plasma. They also don't have the limited lifespan that plasma televisions suffer from, and they're a MUCH more economical choice. (50" DLP ~3k, 50" plasma ~8k, but those are just ballpark estimates). The only reason I would get a plasma is if space was a serious consideration, or if I wanted to mount the tv in an odd place, such as over a fireplace.
The mitsubishi has a beautiful picture, but check the weight on it... the thing is like a battleship! 333 lbs when compared to the DLP 61" which is ~100 lbs. It's also a much deeper set. If space and weight are not limitations, you can get a really nice picture for less money with the mitsubishi.
Anyway, check em out and see how you like the picture on the different types, and make your decision based on that. :)