There are 3 basic pj technologies you can choose from now
DLP
LCD
LCoS
Each technology has pluses and minuses. DLP used to be king in the area of contrast, and in a certain aspect of contrast (referred to as ANSI contrast) it still is I believe.
The contrast capabilities of a projector (or any display tech for that matter) are important because it has a major effect on, among other things, how vibrant and dimensional the image can be. A projector with a poor/low contrast will be muddy and flat looking. During dark scenes, it will be harder to differentiate objects, starfields will look medium grey instead of black, etc
There is also on/off contrast. This generally impacts 'fade to black's. Coming from a projector that had decent ANSI contrast, but poor on/off contrast- I was startled by how impressive a good fade to black can be. This is an effect you don't usually find in the theater even since there are always dimmed houselights somewhere for safety purposes.
LCD and LCoS used to be far behind in both kinds of contrast compared to DLP, but that has turned around in the last few years. Now some of the best projectors in on/off are LCoS. LCD has gotten better, but DLP still leads both in ANSI, though I don't think it is by a great margin anymore.
The one big issue with DLP is the way it works. It uses a spinning color wheel to 'paint' each color on the screen- one at a time, but so fast that the eye combines them. For some people, this creates problems from mild (seeing rainbow trails on areas of the screen) to major (headaches from the color separation artifacts).
I would highly suggest seeing examples of DLPs in person because of this factor.
But then, that's just sound advice in general for any and all projectors. These are a good chunk of change and you should be satisfied and know what you are getting into beforehand.
I would recommend reading up on sites like www.projectorreviews.com. Art should have some good general tutorials there addressing the various technologies and considerations of each.