Before we round up the best projectors, here's some general advice on what to look for before buying. With projectors, as so often with clichés, you get what you pay for. The sheer size of the image they produce means budget models often just don't cut the mustard. So the more you can spend, the greater the rewards.
Once you've chosen your budget, the very first thing to consider is if the models on your short list actually fit the requirements of your room. You need to check that a projector's optics can produce the image size you need from the distance it will sit from the screen. This is known as throw distance.
Projectors with a high optical zoom are often desirable, particularly if you anticipate using it in different locations. The presence of vertical and horizontal image shifting is also extremely important, since this allows you to place the projector above, below or to the side of the centre of your screen without distorting the shape of the image.
Projectors without optical image shifting provide a feature called keystone correction that digitally manipulates misshapen images to return them to the correct, parallel shape. But since this technique is effectively digitally distorting the image, it's not really the best solution if you want the purest image.
We'd recommend your projector has at least two HDMI sockets, and if you're thinking of running it with a motorised screen, a 12V trigger output would be a good idea too.
If you often have a lot of light to compete with in your projection room, look for models with high brightness levels. But if you can get your room really dark, you might find that lower-brightness models can produce richer contrast.
Talking of contrast, you should treat manufacturers' quoted contrast ratios with a hefty pinch of salt -- they really can't be trusted. For instance, while DLP projectors often have lower quoted contrast ratios than LCD projectors, they often produce better blacks.
DLP projectors have their own issues to look out for, though -- most notably the rainbow effect, where the internal colour wheel can cause stripes of red, green and blue to appear over very bright parts of an image, or in your peripheral vision. Plus you can also sometimes see gentle dot crawl over black colours, and fizzing noise over fast-moving skin tones.
In the end, choosing between the main projector technologies is often as much a matter of personal choice as anything else, so try and see examples of each technology in action before buying anything.