There are many quantifiable considerations, but it begins with what your room conditions are.

How large is your room (width/depth/height)?
How far from the screen do you intend to sit?
How large of a screen are you hoping for?
What colors are your walls, ceilings, and floor?
Do you have any external light which comes into the room?
Can you change your wall/ceiling/floor color?
Can you block windows or external light sources completely?
Do you intend to mount the projector to the ceiling?
If so, can you mount it anywhere you want to?

You also want to read through the FAQs at the top of the appropriate forum sections.

http://www.bigscreenforums.com/forum_topic.cfm?which=3088

Right now, at under $2,000 there are some 4K DLP models which are pretty well reviewed, but have somewhat weak contrast. The Sony HW45ES delivers the best image for under $2,000. The Epson 4000 may provide the most flexible 4K placement option.