DLP will certainly give you the best bang for the buck. Most manufacturers have quit making the sets (I believe that Mitsubishi is the only one left), but they provide a really nice picture for a very reasonable price.
The issue of burn-in on plasma sets is controversial. Many people claim it's not an issue at all anymore. However, when I was doing my research into TVs last year, I found a lot of conflicting information. I used the AVS Forum as my main research source. In their Plasma forum, burn-in is still a major topic of conversation. I posted in the Master Burn-in thread and posed a hypothetical question. I asked if burn-in would be an issue if I watched 4x3 material 30% of the time. I got a lot of suggestions to stretch my material and disbelief that I would be interested in watching so much 4:3 material. The bottom line seemed to me to be that many, if not most, plasma owners are still somewhat concerned with burn-in (though it’s supposedly much better than it was) Plasma sets are generally cheaper than LCD, more expensive than DLP.
LCDs have come a long way. They still seem to have some motion blur issues, but they are getting much better in this regard. A lot of the sets use motion processing technology (often referred to as 120 Hz, though this is incorrect). For movies, you ‘re likely better off disabling the motion processing (it can usually if not always be turned off). LCD sets offer a very bright picture, which makes them look particularly good in showrooms. The prices have come down, but good sets are still pretty pricey in large sizes.
If you plan to hang the set on your wall, plasma and LCD are your best bet. However, since you mention DLP, I’m assuming that you don’t plan to do that. If you can handle the size of a DLP set (and they’re really not that large), they really do offer a very good picture and tremendous value.